New York police may have blown the surveillance of a terrorism suspect during a sensitive stage in an FBI investigation, a criminal complaint suggests.

Acting without the FBI's knowledge, police questioned the Muslims' religious leader, Ahmad Wais Afzali.

"They came to ask me about your characters," Afzali told Najibullah Zazi in a secretly recorded Sept. 11 telephone conversation.

Further, the complaint suggests investigators may have tipped off Zazi, by towing and searching a rental car he was using on a New York City trip.

Authorities say that move produced evidence of bomb-making instructions retrieved from a hard drive on Zazi's laptop.

However, it also convinced Zazi that he was being watched, according to the phone conversation with Afzali.

NYPD and FBI officials have denied that missteps forced their hand in the series of terror raids last week.

Zazi, his father and Afzali were arrested over the weekend on charges they lied to the FBI -- but they weren't charged with terrorism.

They have denied the charges against them.