Beijing prosecutors say two police officers have been charged with negligence, nearly two months after a man's death in their custody sparked concern over abuse.

The prosecutor's office said Thursday that an autopsy revealed Lei Yang's suffocation was caused by food content inhaled into his respiratory system, and that police had acted improperly.

The office says police also hampered the investigation but gave no further details.

Lei was questioned on suspicion of soliciting prostitutes in Beijing's suburban district of Changping on May 7.

Police said he refused to cooperate, was forcibly taken into a police vehicle and died suddenly on the way to a police station.