Undercover cop arrested in biker gang attack on SUV

An undercover police officer has been unmasked in a courtroom after being arrested over biker attack

An undercover police officer has been unmasked in a courtroom on Wednesday after being arrested in connection with an assault carried out by a group of bikers.

Detective Wojciech Braszczok, a serving officer for the New York Police Department who has been working under cover for the last five years faces serious assault charges for his part in an attack, which was caught on camera.

Braszczok was off duty when he joined a motorbike rally of 1,000 motorcyclists. An altercation occurred between some of the bikers and Alexian Lien, who was driving through Manhattan, New York with his family.

A motorcyclist allegedly came into contact with Mr Lien’s vehicle during the rally. Video footage shows riders swarming around his car before Mr Lien drives off, running over biker Edwin Mieses Jr.

Mr Mieses broke his legs in the collision and suffered spinal injuries that will leave him paralysed, his family has said. They say he had come off his motorcycle in an attempt to defuse the tense situation when he was hit.

Mr Lien attempted to escape, but was dragged from his Range Rover by bikers and had his head stomped on.

Six men have been arrested over the attack including Braszczok, who as an officer is obliged to report an incident even he is off duty. Braszczok did nothing to stop the assault, prosecutors said.

Investigators discovered video evidence showing Braszczok appearing to punch an already damaged back window, causing it to shatter, then twice kicking the passenger side of the SUV before leaving the scene, prosecutors said.

In a court sketch Wojciech Braszczok is seen in criminal court in New York. (AP)

Several bikers also have been charged with attacking Lien or his SUV or instigating the melee.

Braszczok, 32, has worked to infiltrate the Occupy Wall Street protests since they began in September 2011 under the name Albert.

Shay Horse, a photographer who met Braszczok on an Occupy protest told NBC news he felt “betrayed” by the undercover officer.

“He was down at the smaller occupations we had at the Trinity Church and Occupy Goldman Sachs. He stopped by all those. He was heavily involved and he was at everything. He even came to smaller Occupy parties. He was at everything and anything he could get access to.”

A screen grab from video shows motorcyclists ride alongside a sport utility vehicle (AP)