London  - The man who died after being pushed to the ground by police at this month's London G20 summit died of internal bleeding, not a heart attack as previously said by police, a second postmortem revealed on Friday.

A police officer suspended after the incident has now been interviewed under caution on suspicion of manslaughter, a statement from the Independent Police Complaints Commission (IPCC) said.

Ian Tomlinson, a newspaper seller, was not part of the protests but walking home with his hands in his pockets when pushed to the ground from behind by police on April 1 - an act caught by chance on video.

An initial postmortem had suggested 47-year old Tomlinson died of coronary artery disease, but a subsequent postmortem - carried out at the request of the IPCC and Tomlinson's family - found the death was due to "abdominal haemorrhage."

"The cause of the haemorrhage remains to be ascertained," the IPCC statement said.

The death of Tomlinson has created a political row in Britain, where police at first claimed to have no contact with the dead man, but come under bottle-throwing attack when attempting to resuscitate him.

Instead, subsequent video footage aired by The Guardian newspaper showed a police officer push Tomlinson over from behind in an apparently unprovoked attack.

A rash of subsequent home-made videos from the clashes between demonstrators and police at the protests in the City of London appear to show other examples of police brutality.

One shows an officer hit a woman on the legs with his truncheon at a rally for Tomlinson the next day, April 2.

On Wednesday an officer was suspended in connection with the Tomlinson death. (dpa)