A police officer accused of striking a woman with a metal baton at the G20 protest said he hit her because he felt threatened, a court has heard.

Met Police Sgt Delroy Smellie denies a charge of common assault on Nicola Fisher, 36, of Brighton, at the G20 demonstration in London in April 2009.

The officer told City of Westminster Magistrates' Court he feared objects in her hand were weapons.

The court has been told Ms Fisher was holding a carton of orange juice.

The 47-year-old officer told the court he initially struck the animal rights activist across the face in a move which he described as a "clearance strike".

He said the clash changed the mood of others and he grabbed his metal extendable baton, known as an asp, as the crowd closed in and he was left isolated.

Experience does not negate your ability to feel threatened
Sgt Delroy Smellie

The court heard the senior territorial support group officer then struck Ms Fisher with it when she surged towards him again.

He said he feared objects in her hands could be used as weapons against him.

Asked how hard he hit Ms Fisher, Sgt Smellie replied he was aware she was "significantly smaller".

"However it had to be enough to achieve the objective of negating the threat," he added.

Sgt Smellie told the court he could not remember hitting Ms Fisher a second time, but said his reasons for doing so would have been the same as the first.

'Extremely good officer'

The prosecution allege Sgt Smellie went beyond his legal powers by striking Ms Fisher twice across the leg with the baton.

The clash was caught by several photographs and on video, which was posted on the website YouTube.

Sgt Smellie added: "Even though we have seen umpteen numbers of the video slowed down, it was not slow in reality.

"This was a real situation. It was real time.

"This was fast moving and as much experience as I have, I still felt threatened within the short period of time.

"Experience does not negate your ability to feel threatened."

Earlier, Sgt Smellie's superior Insp Derek Renton described him as an "extremely good officer".

The case continues.

Yet at the same time, said strike looked almost entirely pre-meditated, not the kind of strike you give when you're afraid someone might have a weapon. I don't believe him, and whilst not a supporter of the girl's cause, think the book needs to be thrown at him.

Though that she refuses to give evidence makes me , it's not like she's getting moral highground by doing so.

She kept on going back for more and then held her hand up with something in it... With the crowd baying I'm not surprised the officer felt threatened.

Well he must be a coward to be afraid of an orange juice carton. Not matter how much she mouthed off, assaulting someone is a criminal act.

I don't know the ins and outs, but there could have been a bit more than orange juice in it

Yes but you could always ask the person to drink it.

Not in the middle of a demo/riot you couldn't

Not in the middle of a demo/riot you couldn't

One squirt of lemon juice in the eye is bad enough, let alone a carton of orange juice.

He must have thought that she was a ninja or something.