Washington, Dec 29 (DPA) Al Qaeda has reportedly claimed responsibility for the failed attack on a US airliner on Christmas Day, saying the attempt to blow up the plane was in retaliation for Washington's role in helping the Yemeni government combat militants in the country.

The claim came as Yemen's foreign ministry said late Monday that the suspect in the plot, Umar Farouk Abdulmutallab, had left Yemen earlier in December after attending Arabic language classes there since early August.

IntelCenter, a private firm that monitors terrorist activity, said Al Qaeda in the Arabian Peninsula, or AQAP, posted a statement on a website saying that it was behind the failed plot to blow up Delta/Northwest Airlines Flight 253 as it descended to land in Detroit from Amsterdam Friday.

There were 278 people on the flight. The statement said a "technical error" prevented the device from exploding but they have constructed "advanced explosive packages" that have been tested against airport detectors. The group warned of more attacks against Americans.

"We will strike you with what you have no previous knowledge of, for as you kill you shall be killed, our vengeance is near," the statement said.

AQAP also released a photo of Abdulmutallab, the suspect who has been charged by US federal justice officials with trying to detonate the explosives, and praised him for having the "courage" to carry out the attack.

"His act has dealt a huge blow to the myth of American and global intelligence services and showed how fragile its structures are," it said.

Abdulmutallab, a Nigerian, is believed to have received training and the explosives from Al Qaeda in Yemen. Abdulmutallab reportedly told officials about his connection to the terrorist network, and that he obtained the materials in Yemen, after he was detained Friday.

Yemeni security authorities are now tracing Abdulmutallab's contacts in Yemen, and will give the investigation results to the US anti-terrorism agencies, the foreign ministry said in a statement released in Sana'a.

Yemen, whose government struggles to control the country, has been a growing source of concern for US officials as it appears Al Qaeda has been seeking a foothold there.

The US government has stepped up its efforts to help the Yemeni government fight Al Qaeda, including financial aid and intelligence showing locations of the militants, and there are reports of covert US operations in the country.

"We have a growing presence there ... of special operations, Green Berets, intelligence," Senator Joseph Lieberman said on Fox News Sunday.

"Iraq was yesterday's war. Afghanistan is today's war. If we don't act preemptively, Yemen will be tomorrow's war," he said.