A riot squad officer who hit a G20 protester twice with a metal baton has been cleared of assault.

Metropolitan Police Sergeant Delroy Smellie, 47, clashed with animal rights activist Nicola Fisher outside the Bank of England last April.

The officer, a member of the controversial territorial support group, went on trial accused of assault by beating last week.

Ms Fisher, 36, ran in front of Smellie hurling abuse during a vigil to mark the death of Ian Tomlinson the previous evening.

District Judge Wickham, who heard the case without a jury, watched video footage of the incident and looked at dozens of photographs.

The clash attracted attention worldwide when amateur video footage of it was posted on the YouTube website. Ms Fisher, of Brighton, suffered two bruises to her leg and enlisted Max Clifford to sell her story to a national newspaper for around £26,000.

In his defence, Smellie said he feared for his safety when he was left isolated behind a line of his colleagues who were facing the other way.

The highly-trained and experienced officer, who has been suspended from duty for almost a year, said his actions were reasonable and proportionate.

Smellie said he mistook a carton of orange juice and a camera in Ms Fisher's hands as weapons when she approached from his "blind-side".

Colleagues described him as an exceptional and totally dedicated officer who served as an example to others.