The kidnappers of aid worker Margaret Hassan (search) are threatening to hand her over to Al Qaeda-linked (search) militants notorious for beheading hostages unless Britain agrees within 48 hours to pull its troops from Iraq, an Arabic television station reports.

Early Wednesday, Iraqi police said a Lebanese-American contractor who works for the U.S. Army in the Green Zone (search) was kidnapped from his home in Baghdad's Mansour neighborhood. Armed men knocked on his door and seized the contractor when he answered, said Lt. Col. Maan Khalaf.

Interior Ministry spokesman Col. Adnan Abdul-Rahman identified the victims as Radim Sadeq, a contractor with a mobile phone company.

Also Wednesday, a car bomb exploded near a bus carrying airport employees to work in Baghdad, injuring nine people.

Gunmen also killed an Oil Ministry official, Hussein Ali al-Fattal, in a driveby shooting as he was on his way to work, the ministry said.

On Tuesday, insurgents blew up an oil pipeline and an oil well in northern Iraq in a pair of attacks that shut down oil exports from the north, probably for the next 10 days, Iraqi oil officials said.

A huge explosion rocked the compound of Ghabaza oil field, 22 miles southwest of Kirkuk, late Tuesday night. Earlier in the day, attackers blew up an oil pipeline in northern Iraq that is used for export purposes.

The threat to Hassan, the Iraq director for CARE International, was made in a videotape received by Al-Jazeera television but not broadcast in its entirety because the station said it was "too graphic."

Instead, it transmitted a segment Tuesday night showing a hooded gunman but without sound. The newscaster said the kidnappers gave Britain 48 hours to meet their demands, "primarily the withdrawal" of British troops.

Otherwise, the 59-year-old Hassan will be handed over to Al Qaeda in Iraq, a group headed by Jordanian militant Abu Musab al-Zarqawi. His followers have beheaded at least six hostages: three Americans, a Briton, a Japanese and a South Korean.

Meanwhile, there has been no word on an American and two other foreigners — one Filipino and a Nepalese — abducted Monday night in Baghdad.

In London, Prime Minister Tony Blair's office and the British Foreign Office both declined to comment on the reported demand. Britain has 8,500 troops in Iraq, the second-largest contingent after the United States.

Irish Prime Minister Bertie Ahern told his parliament that the full tape showed the Dublin-born Hassan pleading for her life directly to the camera before suddenly fainting.

Ahern, who had not seen the video, said a bucket of water is then thrown over Hassan's head and she is filmed lying wet and helpless on the ground before getting up and crying.

Ahern described the text of the video as "distressing" and said "there were a number of very dangerous and very serious timescales stated."

Hassan, an Irish-British-Iraqi citizen who is married to an Iraqi, was kidnapped last month from her car in western Baghdad. No group has claimed responsibility for her kidnapping and there was no sign on the brief broadcast of any banner identifying who held her.

Her captors previously released three videos of Hassan, and in two of them she pleads for her life, saying she fears she will be beheaded. But she does not say when, and none of her kidnappers have appeared in any of the tapes.

The threat against Hassan was made public three days after the decapitated body of Japanese backpacker Shosei Koda was found in a field in northwestern Baghdad. A videotape posted Tuesday on the Internet in the name of al-Zarqawi's group showed the 24-year-old Japanese thrown to the floor and beheaded on an American flag.

Al-Zarqawi's group is believed based in Fallujah, the militant stronghold 40 miles west of Baghdad. U.S. forces are gearing up for an assault against Fallujah unless the city surrenders al-Zarqawi and other militants. Sunni clerics who run the city insist he isn't there.

U.S. and Iraqi forces hope to clear Fallujah and other Sunni militant strongholds north and west of Baghdad so that national elections can be held in January. U.S. forces have pounded insurgent positions around Fallujah almost daily, but American officials say the go-ahead for an all-out assault must come from interim Prime Minister Ayad Allawi.

However, new pressure mounted Tuesday on Allawi, a Shiite Muslim, to forego an assault and to continue negotiating with the hardline Sunni clerics who run the city, which has become a symbol of Iraqi resistance throughout the Arab world.