Amid reports that up to 80 American students are getting training in a Taliban-backed madrassa in Pakistan, a group of lawmakers on Friday said the matter is of "tremendous concern" for security of the US.

The panel of lawmakers on Homeland Security, during a hearing, expressed their concern at various reports including that of American children with legal passports getting training in madrassas in Pakistan with a view to getting back into the US.

"That is of tremendous concern as well," a lawmaker said referring to the reports.

Homeland Security Committee Secretary Michael Chertoff said the goings on in the northern tribal areas of Pakistan is of serious concern to the US.

Chertoff said there is nothing more important than addressing this issue as it has direct implication to the security of Europe and America.

"What is going on in the frontier areas there is... at the top of my list of concerns about where our next few years are with respect to international terrorism," Chertoff told the a panel.

"The more time and space Al Qaeda [Images] has and its militant allies... Ayatollah Massood... the others -- the more time and space they have to train and plan and operate and experiment, the more problems we're going to have in the pipeline headed both towards Europe and towards us," he said.

"And that's from a foreign policy standpoint, from Homeland Security's standpoint, that's got to be -- there's nothing more important than addressing that issue," Chertoff added.