There are 20 more plane bombers ready

Twenty other young Muslim radicals have been trained to blow up planes by Al Qaeda in Yemen, a young Nigerian charged with trying to blow up a US airliner has told FBI.

Umar Farouk Abdulmutallab, 23, has told FBI that close to 20 other young Muslim men were being prepared in Yemen to use the same technique to blow up airliners, CBS said in an exclusive investigative report.

The Nigerian terror suspect was arraigned on Friday in a Detroit court on charges of blowing up a North West Airlines plane on December 25.

Abdulmutallab earlier pleaded not guilty to six charges arising out of the botched Christmas Day bombing of Northwest Flight 253 from Amsterdam to Detroit.

The Nigerian allegedly stitched two highly explosive substances into his clothes, and tried to detonate them as the plane carrying 290 people approached Detroit. But the device failed to detonate.

"I think the fact we know that there are other operatives being trained by Al Qaeda in Yemen is extremely troubling, and is the most dangerous dimension to come out of the December 25th event," CBS said.

The television network quoting US officials said that is why the government issued directive about pat down searches of "every individual" coming to the US from 14-terror suspect countries.

CBS News also reported that a FBI team is in Ghana, as part of the ongoing investigation against the December 25 terror plot.

"US officials strongly suspect Abdulmutallab met Al Qaeda operatives in Ghana who may well have given him the specially-designed underwear packed with highly explosive powder," the report said.

"One of the keys is to get to London, to Ghana, to Nigeria, to Yemen to find out who Abdulmutallab was talking to, what he was doing, what else may be at play here with respect to a pipeline coming out of Yemen to hit the United States," CBS said.