CIVIL rights group Liberty warned of a grab for “wacky and dangerous” new powers yesterday after Britain’s top cop Sir Bernard Hogan-Howe said extremists who fight abroad should be stripped of their passports.

The Met Police Commissioner declared on London radio that “if you’re going to start fighting in another country on behalf of another state or against another state, it seems to me that you’ve made a choice about where you want to be.”

But Liberty policy officer Rachel Robinson warned against a measure — rejected by Deputy Prime Minister Nick Clegg — that was more “a tool of dictators not democrats.”

She said any step towards such a plan would risk “terrible injustice for the innocent.

“And why is our most senior police officer wading into politics anyway?

“The police are meant to enforce the law impartially, not lobby for wacky and dangerous new powers.”

A Home Office spokesman said that the government was taking “the strongest possible action to protect our national security” against extremists returning to Britain.