A woman filmed being hit by a baton-wielding police sergeant during protests at the G20 summit in London said on Saturday the officer who attacked her used unnecessary violence and aggression.

In a series of television interviews, Nicola Fisher said the policeman pushed her, struck her across the face and then hit her on the legs with a baton.

A police sergeant from London's Metropolitan police was suspended on Wednesday after footage of the incident, which took place on April 2, was made public on the website Youtube.

"He pushed me, and I pushed him back. It was sort of an automatic reaction -- I was shocked that he pushed me. And then straight away, he back-handed me on my left cheek, and that made me very angry," Fisher, a 35-year-old from Brighton, south east England, told Sky television.

She said she reproached the officer, asking him what he was doing hitting a woman, and said she "probably" swore at him.

"And then he got the baton out, shook it, and hit me over the back of my leg. I stumbled backwards ... and he hit me again."

In a separate interview on BBC television, Fisher described the attack as forceful. "It wasn't a tap, he used his full force. It was very violent and very aggressive and very unnecessary," she said.

"I was just so angry and shocked that he had done it and to be honest, I really didn't think he was going to get his baton out and hit me like he did."

Britain's Independent Police Complaints Commission (IPCC) police watchdog said on Friday that another Metropolitan police officer had been questioned on suspicion of manslaughter over the death of a man in the G20 protests on April 1.

The IPCC says it has received a total of 145 complaints about the policing of the April 1 and April 2 protests, which saw confrontations between anti-capitalist demonstrators, environmental campaigners and riot officers.

It said an unnamed officer was questioned under caution after a second post-mortem found that newspaper seller Ian Tomlinson had not died from a heart attack as first thought.

Tomlinson, 47, died after being caught up in protests near the Bank of England in the heart of London's financial district as he made his way home on April 1, the day before world leaders gathered to discuss the economic crisis.

Video footage taken by a New York fund manager showed Tomlinson, who had not taken part in the demonstrations, being shoved to the ground by a police officer in riot gear. He collapsed shortly afterwards in a nearby street.

The capital's police chief has expressed his concern about the video images and has ordered a review of public order tactics, especially the use of "kettling" where protesters are herded by officers into a confined space.

Reuters