A police officer accused of hitting a student over the head with his baton during a protest has told a misconduct hearing he believed his "life was at risk".

Alfie Meadows, 29, who was then studying philosophy at Middlesex University, suffered a head injury requiring emergency surgery.

Detective Constable Mark Alston, 37, denies striking Mr Meadows during the demonstration against student fees in London on December 9 2010.

The officer, who is accused of using unreasonable force, told a misconduct hearing in central London on Tuesday: "I was in a situation where I believed my life was at risk and that of other officers.

"I was in a situation which was really crowded.

"I was trying to do my best to defend myself and my colleagues."

He was a 26-year-old Pc when he was deployed to police the protest, which saw violent clashes in and around Parliament Square.

"Initially it was OK but as the day drew on it became more hostile," he said.

"I could tell the situation was starting to escalate.

"It's like a gut feeling you get that the situation is getting worse.

"It's like a sixth sense."

Mr Alston said he went into the crowd with colleagues to rescue a group of officers after the commanding officer said there was a "risk of serious injury or death".

He told how he drew his baton as missiles were "raining" down and feared he could be injured by metal barriers being pushed towards him by protesters.

"It was a dire situation. It was really high-risk," he said.

"There were bits of masonry, concrete, glass bottles and fireworks being thrown at us."

Video footage is said to capture the moment he raised his baton in a "violent, uncontrolled and dangerous manner" before striking Mr Meadows.

The hearing has been told officers are taught to swing their batons using a sideward motion, targeting arms or legs.

Mr Alston can be seen with the weapon raised in the air before bringing it down, although the alleged moment of contact cannot be seen.

"To the best of my recollection I didn't hit anything," he said.

"As far as I can remember it went downwards and I didn't strike anyone at that point."

Stephen Morley, representing the City of London police, who are bringing the case against Mr Alston, suggested the footage showed the officer striking his baton four times in six seconds towards the crowd.

"This is pretty indiscriminate.

"You are just lashing out at the crowd in front of you," the lawyer suggested.

"You are just whacking students."

Mr Alston denied the suggestions.

Mr Meadows, who is studying for a master's degree in philosophy, needed more than 100 staples in his head and was left with a large scar.

He was charged with causing violent disorder and taken to court where he was cleared by a jury in 2013.

A probe by the police watchdog, now called the Independent Office for Police Conduct (IOPC), found Mr Alston had a case to answer for gross misconduct, but City of London police rejected the recommendation.

The force then failed in a court bid to challenge the IOPC's direction that he should face a full hearing.