Cops: Leona Lewis Attacker Has Mental Issues

Here's a shocker -- cops say the guy arrested for slapping pop singer Leona Lewis in the face yesterday may not be right in the head.

Officials at Scotland Yard claim they just charged 29-year-old Peter Kowalczyk with common assault and "sectioned" him under the mental health act -- which means he's being held so doctors can evaluate him.

As TMZ previously reported, Lewis was taken to the hospital Wednesday as a precaution after the attack at a book signing in London.

As of now, Peter is due back in court October 26.