A 28-year-old man has admitted kicking a woman down the stairs at a Berlin underground station at the start of his trial on Monday, in an incident that caused an outcry in Germany.

He said that he had no concrete memory of committing the crime and only became aware of it later when video footage from the underground station was made public, according to a statement read out in Berlin's regional court by one of his defence team.

He claimed to have been under the influence of alcohol and drugs at the time of the crime and said he wanted to express his apologies to the woman.

The accused kicked the unsuspecting 26-year-old woman violently in the back as she was descending the stairs into the underground station one night at the end of October, sending her flying to the bottom and resulting in a broken arm and a head injury.

The incident was recorded on security cameras at Hermannstrasse station in the city's Neukoelln district.

The man, who comes from Bulgaria, is also accused of exposing himself in the underground station two weeks beforehand. He refused to comment on these charges.

The trial had initially been scheduled to start 10 days ago, but was adjourned when the defence team successfully challenged one of the female jury members on the grounds of bias.