An American teacher who was attacked by Austrian police who mistook him for a drug dealer said Monday he believes he was attacked because he was black and he is taking legal action against the police for assault.

Mike Brennan, 34, from Jacksonville, Florida, said two undercover police officers "came out of nowhere" at a Vienna subway station and attacked him without identifying themselves.

Vienna police admitted the mix-up Monday and expressed their regret. In a statement, they acknowledged the officers had used "physical force." An investigation is under way.

Brennan is recovering in a hospital from bruises, swelling and sprains to his back, neck and hand.

Asked in an interview with The Associated Press whether he believed he was attacked because of his race, Brennan said he saw "hatred" in the eyes of one of his attackers.

"I heard about the situation before here, I heard a lot about it, and I've never really seen it" before, he said.

Brennan teaches physical education and English as a Second Language at the Vienna International School, a private school that caters to the Austrian capital's expatriate community. He has lived in the Austrian capital for about four years.

He said he would have been more badly injured if his girlfriend had not intervened.

"I don't want this to happen to anyone else — I hope justice is served," said Brennan, perched on the edge of his hospital bed holding crutches.

"I was bent over ... I had very excruciating pain," he said.

Brennan's lawyer Alexander Hofmann said he had initiated legal action against police for abuse of power and assault and battery.

He said that when police realized Brennan was not the man they were looking for, they left the scene, leaving him injured.