Three Japanese and two Israeli Arabs were being held hostage Thursday by Iraqi militant groups, but seven South Korean evangelical Christian missionaries were freed by a third set of gunmen.

A Briton was also reported kidnapped in a fourth incident.

The seizures could have wider implications for U.N. workers, journalists, as well as missionaries, security personnel and those doing business with the Iraqi government. At least one of the Israeli Arabs works for a U.S. aid organization.

The Japanese government said the hostage-taking would have no effect on its plans to keep troops in Iraq, and both the Israeli government and the Palestinian Authority were said to be working toward freeing the Israeli Arabs, whose citizenship was not clear.

Al-Jazeera, the Qatar-based Arabic-language satellite news channel, aired a video from a group called Saraya al-Mujahedeen (search), or "Squadrons of Holy Warriors," which showed two Japanese men and one woman, dressed in civilian clothing.

The kidnapped trio, squatting in a bullet-riddled room surrounded by several heavily armed, hooded men, were blindfolded in one video shot and wide-eyed in another. They screamed and whimpered as the gunmen shouted "Allahu Akbar!"

Associated Press Television News obtained a copy of the full tape, which showed the hooded men pointing knives and swords at the captives' chests and throats.

The tapes obtained by Al-Jazeera and APTN were silent, but a copy broadcast on the U.S.-backed Arabic satellite channel Al-Hurra had audio.

Open Japanese passports were held up to the camera, identifying the three as Nahoko Takato, 34, Noriaki Imai, born 1985, and Soichiro Koriyama, 32. A press card for Koriyama from the weekly newspaper Asahi was also displayed.

Al-Jazeera editors said the three were taken hostage in southern Iraq, where black-clad Shiite militiamen have been engaged in an uprising this week.

Japanese state broadcaster NHK said Takato, the woman, was a foreign aid worker with a human-rights group who had been working with Iraqi children for several months.

NHK said Imai had been doing research on the effects of depleted-uranium weapons in Iraq, while Koriyama was a freelance cameraman.

On the tape, a gunman holds a knife to the throat of one of the men; his eyes widen in panic and he struggles to try to get free. The woman screams and weeps.

Al-Jazeera (search) said the group was giving Japan three days to withdraw its troops from Iraq before it killed the hostages.

"Three of your sons have fallen into our hands," the Al-Jazeera announcer said, quoting a statement he said came with the silent videotape. "We offer you two choices: Either pull out your forces, or we will burn them alive. We give you three days starting the day this tape is broadcast."

In Tokyo, a Japanese government spokesman said Thursday that despite the reported kidnappings, Japan had no reason to withdraw its troops from Iraq. He also demanded the immediate release of the three Japanese hostages.

Japanese lawmakers said the three were kidnapped by a terrorist-related group, according to the news agency Kyodo.

"The only thing I can say is we watched Al-Jazeera," Japanese Foreign Ministry spokesman Hatsuhisa Takashima told Reuters, "and what Al-Jazeera reported is what we are now trying to confirm."

South Korea's foreign ministry confirmed Thursday that seven evangelical Christians had been held, then freed less than a day later, in Iraq by an armed group, according to the Yonhap news agency.

"All of the seven captured South Koreans were freed," a ministry official said. "Three of them arrived at the Palestine Hotel in Baghdad, and the others are on the way."

Eight missionaries, who had left for Iraq on April 5, were initially detained late Wednesday evening, but one later escaped, South Korea's Ministry of Foreign Affairs and Trade said.

The South Korean Kyodo news agency identified the seven as: Huh Min Young, Lim Young Seok, Hong Gwang Cheon, Cho Jeong Kyon, Lee Myung Sook, Kim Pil Ja and Byun Kyong Ja. It said they were believed to be evangelists from the Christian Council of Korea (search).

The eight were traveling in two cars from Amman, Jordan, when they were seized about 155 miles west of Baghdad, said the escapee, identified by Yonhap as Kim Sang Mi, from a church in Incheon.

South Korean TV station SBS reported from Iraq that the armed men held the Koreans for nine hours and freed them when they learned they were missionaries.

One of the freed group, a middle-aged man, told Associated Press Television News that the captors, who wore masks, treated them well.

"First, I felt insecure, but later they made us feel comfortable and gave us food and drinks," the man said in Baghdad. "I think at first they thought we were linked to U.S. soldiers."

Israeli media reported that two Arab residents of Jerusalem had been kidnapped by Iraqi insurgents, and video showing the two held hostage, first shown on Iranian TV, was rebroadcast in Israel.

It was unclear whether the two were Israeli citizens. The Haaretz Web site said the video showed photographs of the men's documents, which included two Israeli ID cards, an Israeli driver's license, a state of Georgia driver's license, a local health insurance card and a supermarket-chain discount card.

Haaretz quoted the Iranian al-Alam TV station as identifying the pair as Ahmed Yassin Tokati, 33, and Nabil George Yaakub Razuq, 30, both Arab Christians from East Jerusalem. The TV station said they were kidnapped by a group calling itself Ansar al-Din (search), or "Supporters of the Faith."

The Jerusalem Post Web site quoted the men's kidnappers as saying their hostages were "agents of the Zionist enemy" and demanding the freeing of prisoners held by the U.S.-led coalition.

Both men said on television that they were international aid workers, according to Haaretz. Their families told Israeli TV they had no idea the pair were in Iraq.

Gideon Ezra, Israel's Minister Without Portfolio, told Israel's Channel 2 television that the two men were not Israeli citizens, but that the government would use diplomatic means to get them "out of the clutches of evil."

"They are not Israeli citizens," Ezra told Channel Two television. "They are not couriers or agents of the Mossad."

Israel's Channel 2 reported that at least one of the men's relatives had asked Palestinian Authority leader Yasser Arafat to try to intervene.

Israeli Army Radio broadcast an interview with Razuq's uncle, Samir Razuq, who said his nephew was an Israeli citizen and passport-holder who had worked in Israel for the U.S. Agency for International Development, or USAID.

Other relatives told reporters that Razuq had gone to college in Georgia.

Samir Razuq added that his nephew lived in the Beit Hanina neighborhood of East Jerusalem and was married to a Czech woman.

Another uncle, identified as Anton Razuq, spoke to the Associated Press.

"I am very worried. I pray for his safety," the uncle said. "I want to tell the Iraqis he is not a spy, not for America and not for Israel. He is an Arab, a member of the Arab nation, a Palestinian like me living in Jerusalem under Israeli occupation."

Arabs who live in East Jerusalem, which Israel annexed after the 1967 Six-Day War, are considered residents of Israel and are eligible for Israeli citizenship, which few take.

The British civilian was seized earlier this week near the southern Iraqi city of Nasiriyah, according to Reuters.

The man, identified as 37-year-old Gary Teeley, a civilian contractor, was said to have been working at a U.S. airbase, but a British Foreign Ministry spokesman refused to give more details.

"He is missing. We were first made aware of this on Monday, April 5," a spokeswoman told Reuters. "We are in touch with his next of kin and the appropriate military and civilian authorities. I don't have any further information."

Italian troops and paramilitary police in Nasiriyah have been engaged in heavy fighting this week with members of Muqtada al-Sadr's al-Mahdi Army, a radical Shiite Muslim militia.

Japan has about 530 ground troops based in Samawah, part of a total planned deployment of 1,100 soldiers for a mission in Iraq to purify water and carry out other reconstruction tasks.

Japanese Prime Minister Junichiro Koizumi (search) has been one of the strongest backers of the U.S.-led invasion of Iraq, a stance that has raised concern Japanese troops could be targeted by insurgents in that country.

About 460 South Korean medics and military engineers have been in Nasiriyah for almost a year. They will come home after South Korea sends a new deployment of up to 3,600 troops to the Kurdish region of northern Iraq later this year.

The kidnappings came amid escalating violence in Iraq. Earlier this week, two South Korean aid workers were briefly detained by Shiite forces during a gunbattle with Italian peacekeepers. They were released unharmed.

FoxNews.com's Paul Wagenseil and the Associated Press contributed to this report.