BUCHAREST, Romania — Police say they have arrested a Romanian high school principal on suspicion she took bribes from students taking final exams, an investigation that involved intelligence officials bugging the faculty lounge.

Thirty-seven teachers and supervisors at Bucharest's Dimitrie Bolentineanu high school were also questioned Tuesday, a day after Principal Costica Varzaru was fired.

According to the police statement, the country's main domestic spying agency, the Romanian Intelligence Service, bugged the school three weeks ago after getting a tip about a bribe operation.

Police searched teachers and test monitors at the school Monday as students sat for the Romanian pre-university exams. They found money suspiciously hidden in underwear, cupboards and bags.

It was not immediately clear who was representing the principal, who could not be directly reached Tuesday.

Romania, which has seven intelligence agencies, has been under pressure from its fellow European Union members to crack down on corruption.