Baghdad, Iraq ? An al-Qaida linked group threatened in a videotape Saturday to behead two Americans and a Briton within two days, and insurgents carried out a new string of car bombings, killing at least 20 Iraqis and two American soldiers.

The unrelenting violence has taken 300 lives in the past week.

The videotape was the first word on the fate of Americans Jack Hensley and Eugene Armstrong and Briton Kenneth Bigley since the three construction workers were kidnapped two days earlier from their Baghdad home.

“My job consists of installing and furnishing camps at Taji base,” each man said in turn after identifying himself, as all three sat on the floor, blindfolded, slightly bowed but apparently unharmed. At one point, a militant’s rifle pointed down at the head of the man who identified himself as Hensley.

The Tawhid and Jihad group, led by Jordanian militant Abu Musab al-Zarqawi, claimed responsibility for the abduction and demanded the release of Iraqi women detained in two American prisons.

The videotape was broadcast by Al-Jazeera shortly before it revealed a fresh kidnapping claim. Another group claimed it had kidnapped 10 workers for an American-Turkish company and threatened to kill them in three days if their firm didn’t leave Iraq.

Kidnappings and spectacular bombings have become the signature weapons of insurgents waging a 17-month campaign against U.S. and Iraqi forces, a campaign that has persisted since the interim government of Prime Minister Ayad Allawi took power in June.

Nevertheless, Allawi insisted U.S. and Iraqi forces were winning the fight and said progress would be made to calm the violence before crucial elections set for January.

The insurgency is “not getting stronger; it’s getting more desperate. We are squeezing out the insurgency,” Allawi said, speaking in an interview due to be aired today on ABC’s “This Week.”

“We are winning. We will continue to win. And we are going to prevail,” he said.

Guerrillas have struck with increasing sophistication in Baghdad, the center of Allawi’s authority, and have dealt punishing blows against Iraq’s security forces — which are the lynchpin of the U.S.-Iraqi strategy for fighting the insurgency.

Insurgents set off a car bomb Saturday on the road to Baghdad’s airport near an overpass as a U.S. convoy passed, wounding three U.S. soldiers. When other American troops moved to the scene, another car bomb exploded, killing two soldiers and wounding eight more.

In the northern city of Kirkuk, a car sped at a crowd of would-be recruits lined up at the offices of the Iraqi National Guard. Guardsmen opened fire on the vehicle and it exploded, leaving the street strewn with bloodied bodies, twisted metal and shards of glass.

At least 19 people were killed and 67 wounded, the Health Ministry said.

It was the third bombing of the week targeting the beleaguered security forces, seen as collaborators with the United States and its allies.