Gunmen in Iraqi army uniforms burst into Red Crescent offices on Sunday and kidnapped more than two dozen people at the humanitarian organization in the latest sign of the country's growing lawlessness.

British Prime Minister Tony Blair, in Iraq on his sixth visit since the 2003 invasion, appealed for international support for Iraq's fragile government, saying the bloodshed was being carried out "by the very forces worldwide who are trying to prevent moderation."

Blair and his Iraqi counterpart, Nouri al-Maliki, discussed preparations by British military units in Basra, the main city in southern Iraq, to turn over security to Iraqi forces. Britain expects to withdraw several thousand troops from Iraq next year, despite concerns that Iraqi forces are not ready to keep order on their own.

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"Our task — ours, the Americans, the whole of the coalition, the international community and the Iraqis themselves — is to make sure that the forces of terrorism don't defeat the will of the people to have a democracy," Blair said.

In the latest violence, gunmen in five pickup trucks pulled up at the office of the Iraqi Red Crescent in downtown Baghdad and abducted 25 employees, police said. A Red Crescent official, who spoke on condition of anonymity because of safety concerns, said the gunmen left women behind.

Pierre Kraehenbuehl, director of operations of the International Committee of the Red Cross, said in Geneva that seven abductees were released. The Dutch Foreign Ministry said three Iraqi security guards at its embassy building in Baghdad — adjacent to the Red Crescent offices — were also kidnapped, but were later released.

The Red Crescent, which is part of the international Red Cross movement, has around 1,000 staff and some 200,000 volunteers in Iraq. It works closely with the International Committee of the Red Cross, which visits detainees and tries to provide food, water and medicine to Iraqis.

"We don't know who they are. We don't know why they did this," said Antonella Notari, a Red Cross spokeswoman in Geneva.

She also said the organization was in contact with the Iraqi Interior Ministry, which denied any involvement and had assured that they were searching for the abductees.

Mazin Abdellaha, secretary-general of the Iraqi Red Crescent, appealed to the kidnappers to release the captives.

"They represent a humanitarian agency that works for the general good, and this agency helps all people regardless of their sect or ethnicity," Abdellaha said.

At least half a dozen mass kidnappings have been carried out in the Iraqi capital this year, possibly by armed groups linked to the sectarian conflict between Sunnis and Shiites.

The abduction comes just days after the organization's vice president, Dr. Jamal al-Karbouli, said American forces represented a greater danger to its work than insurgents.

"The insurgents, they are Iraqis, a lot of them are Iraqis, and they respect the Iraqis. And they respect our (the Red Crescent's) identity, which is neutrality," al-Karbouli said Friday.

Lt. Col. Christopher Garver, a U.S. military spokesman in Baghdad, said in response that the U.S.-led coalition forces "strive to ensure they are respectful when they conduct interaction with the local population."

On Thursday, gunmen in military uniforms kidnapped dozens of people in central Baghdad, police said. The attackers drove up to the busy Sanak area in about 10 sport utility vehicles and began rounding up shop owners and bystanders. Police said 50 to 70 people were abducted, but at least two dozen were later released.

On Sunday, the U.S. military said a roadside bomb killed three American soldiers and injured a fourth serviceman north of Baghdad. The soldiers were clearing a route so another unit could move through the area on Saturday, the military said in a statement.

The toll raised to 57 the number of Americans killed in Iraq in December. At least 2,945 members of the U.S. military have died since the U.S.-led invasion in March 2003, according to an Associated Press count.

British and Iraqi troops in Basra are conducting a neighborhood-by-neighborhood sweep aimed at rooting out weapons and militants and launching reconstruction projects. Its completion in the new year will likely trigger an announcement that Britain is slashing its troop numbers.

Britain has some 7,000 troops in Iraq, most based around the city of Basra in the south — the largest commitment of any country after the United States. More than 120 British personnel have died in the country since the U.S.-led invasion in 2003 that ousted Saddam Hussein.

"The operation there for the Iraqi forces to take control of security of the city is going well," Blair said.

Late on Sunday afternoon, Blair flew to Basra to visit some of the troops stationed there.

"Our country and other countries like it are having to rediscover what it means to fight for what you believe in," Blair told the soldiers.

"You are not fighting a state, but fighting a set of ideas and ideologies, a group of extremists who share the same perspective," he said.

Among those killed in violence were two policeman, an Iraqi soldier and a municipal official in Baghdad; and a police officer in Kut, southeast of the capital.

Complete coverage is available in FOXNews.com's Iraq Center.