BY MARTIN WILLIAMS and MICHAEL SETTLE The police officer seen in video footage striking Ian Tomlinson has identified himself to investigators, a spokesman for the Independent Police Complaints Commission said last night.

The officer was seen hitting Mr Tomlinson with his baton during the G20 riots in the City of London last week and pushing him to the ground. Mr Tomlinson later collapsed and died.

IPCC Commissioner and deputy chairman Deborah Glass said: "Several police officers, including the officer himself, have come forward. It is our intention to interview this officer as soon as possible."

A Scotland Yard spokesman said: "Earlier today a Metropolitan Police Service officer identified himself to his team leader as being potentially involved in the incident shown on the video footage. A total of four MPS officers, inclusive of this officer, have now come forward with potentially relevant information in relation to the investigation into the death of Mr Tomlinson."

Meanwhile. footage shown by Channel 4 News last night showed a riot officer seemingly striking out at Mr Tomlinson with a baton before pushing him to the ground.

Previous footage, obtained by a newspaper, showed Mr Tomlinson being hit and pushed over by a partially masked officer as he walks away from a police line with his hands in his pockets.

The new footage, taken by a Channel 4 News cameraman, shows an officer apparently striking him left-handed with a baton, then shoving him to the ground.

Former London mayor Ken Livingstone told the same programme: "Not only should this officer be suspended immediately, but officers who refuse to co-operate with this investigation cannot continue to expect to police the streets of London."

He added that this was "random casual violence on the part of the officer concerned".

Scotland Yard said last night that no officers had been suspended over the incident.

The IPCC said a number of officers captured on camera when the 47-year-old newspaper seller was struck had yet to come forward.

The watchdog has ordered a second post-mortem examination in a bid to determine if there was any external factor behind his fatal heart attack.

Photographer Anna Branthwaite said Mr Tomlinson was manhandled about 15 minutes earlier as he tried to cross a police cordon on his way home from work.

She told another newspaper he was shoved to the ground and struck twice with a baton before being picked up by the officer and pushed along the street.

The video images of Mr Tomlinson's last minutes provoked outrage and sparked fresh questions about police containment tactics during the angry April 1 demonstrations.

Last night, Mark Lazarowicz, the Labour MP for Edinburgh North and Leith, added his voice to the calls for a full independent inquiry.

"A lot of constituents have contacted me about this, and having looked at the video of the incident, I can understand their concerns," said Mr Lazarowicz.

Metropolitan Police Commissioner Sir Paul Stephenson said the images "raise obvious concerns" while Home Secretary Jacqui Smith called for a fast and effective inquiry.

Mr Tomlinson's stepson has demanded answers and called for the officer responsible to be "pulled in".

Paul King, 26, said his father left work selling newspapers at Monument Tube station at about 7pm but was prevented from getting home by police barricades.

He told BBC Radio Five Live: "I can see my dad Ian has his hands in his pockets with his head down walking away, so there was no reason for the officer to push him in the beginning."