A television image aired by Al Jazeera June 27, 2004 shows a blindfolded man dressed in camouflage sitting in a chair with a hand holding a sword above his head. A Marine Corps identity card named him as Wassef Ali Hassoun. (Reuters photo)

Iraqi militants have allegedly kidnapped a US marine and threatened to behead him unless Iraqi prisoners are released, al-Jazeera Satellite TV reported on Sunday.

A group, which called itself the "Islamic Retaliation Movement", was quoted as saying that the marine of Pakistani origin would be executed unless detainees in US-led coalition prisons are freed.

The name of the captive was Hasun Wassef Ali and he was abducted outside a Marine base, the group claimed.

In a video footage aired by Arabiya news channel earlier on Sunday, an unknown armed group announced that it was holding a Pakistani hostage and he would be beheaded if prisoners detained in Iraq are not released in three days.

"You must release our prisoners held in the US base in Balad, Dujail, Yathrib, Samarra and Abu Ghraib and you have three days from now on and after that we will behead him," said the group.

The Pakistani, a driver working with the US-led coalition and entering Iraq from Kuwait, was taken hostage near Balad in northern Iraq, mentioned the group.

Also Sunday, militants hit a coalition transport plane with small arms fire after takeoff from Baghdad's airport, killing an American passenger and forcing the aircraft to return.

Turkey rejected demands by militants threatening to behead three Turkish hostages unless Turkish companies cease business with US forces in Iraq.

The Pakistani driver was shown earlier Sunday on a tape broadcast by a different Arab television station, Al-Arabiya. The hostage displayed an identification card issued by the US firm Kellogg, Brown & Root, a subsidiary of Vice President Dick Cheney's former company Halliburton.

Four masked men holding assault rifles across their chests said they would behead the Pakistani within three days unless Americans freed prisoners held at Abu Ghraib and three cities of central Iraq - Balad, Dujail and Samarra.

The gunmen said they captured the Pakistani near the US base at Balad, 50 miles north of Baghdad. They did not say whether they were affiliated with any group, The hostage, who gave his name as Amjad, urged Pakistani President Pervez Musharraf to close the Pakistani Embassy in Iraq and to ban Pakistanis from coming to Iraq.

"I'm also Muslim, but despite this they didn't release me," he said, bowing his head. "They are going to cut the head of any person regardless of whether he is a Muslim or not."

It was unclear how either set of kidnappers was linked to Jordanian terror mastermind Abu Musab al-Zarqawi, who claimed responsibility for the decapitation deaths of American businessman Nicholas Berg and South Korean translator Kim Sun-il last week.

In Baghdad, meanwhile, an American soldier was killed Sunday when a rocket slammed into a US base on the southeastern outskirts of the city, the military said.

Threats against hostages as well as attacks on US and Iraqi security forces have accelerated as Iraq's interim government prepares to assume sovereignty Wednesday.

Gunmen dressed in black killed six soldiers of the Iraqi National Guard, formerly the Iraqi Civil Defense Corps, and wounded four others at a checkpoint in Jalawla, 75 miles northeast of Baghdad.

In first reports of the attack on the transport plane, US military officials said the aircraft was American. Later, however, Australia's Nine Network television said it was a C-130 transport from the Royal Australian Air Force. The plane was about 12 miles from the Iraqi capital when it was fired on and forced to return to Baghdad International Airport.

Australia Broadcasting Corp. radio reported that a passenger on the plane who died of injuries was a US citizen. US Brig. Gen. Mark Kimmitt also said the victim was believed to be an American, according to the report.

Attacks against coalition aircraft around Baghdad have occurred before, although no fixed-wing planes have been shot down. The main road linking the airport to central Baghdad also has become increasingly dangerous because of ambushes.

In Istanbul, Turkish Defense Minister Vecdi Gonul rejected demands by al-Zarqawi's group for Turkish companies to quit doing business with US troops in Iraq to spare the lives of the three Turkish hostages.

"Turkey will not bow to pressure from terrorists," Gonul told the private CNN-Turk and TV8 television stations.

The demand was issued as Bush and other Western leaders gathered in Turkey for a NATO summit Monday. Turkey, the only Muslim nation in NATO, was put in a difficult position trying to balance alliance solidarity with national interests.

The US mission in Iraq is deeply unpopular in Turkey, and it was feared that any killing of Turkish hostages could intensify anger against the United States.

More than 40 people from several countries have been abducted in Iraq since April - many of them released or freed by coalition soldiers. Several kidnappings have been blamed on the al-Zarqawi group.

Elsewhere Sunday, three rockets exploded near one of Saddam Hussein's former palaces in the Green Zone, the heavily guarded headquarters of the US-run occupation. US officials said the blasts caused no damage or casualties.

At sunset, guerrillas fired a second volley of several mortars into the heart of Baghdad, killing two children playing near a bank of the river Tigris, an Interior Ministry official said.

Three mortar shells also fell in the northern city of Mosul, hitting an office of the Patriotic Union of Kurdistan, a pro-US political party. One party member was killed and nine others were injured, including two civilians.

Also in Mosul, gunmen killed a policeman in a drive-by shooting, police said. In a separate attack, gunmen struck an Iraqi army recruiting with rifle-fire in another drive-by, injuring one guard.