A British court on Monday jailed for two weeks a football fan who urinated next to a terror attack memorial during clashes between far-right protesters and the London police.

Andrew Banks, 28, pleaded guilty to one count of outraging public decency for urinating by the side of a plaque dedicated to Keith Palmer, a police officer killed in the 2017 Westminster Bridge attack outside parliament.

The incident, first captured on social media, came during clashes involving self-styled "patriots" backed by far-right groups who had gathered Saturday to counter anti-racism protesters in central London and "protect" public statues.

Prosecutor Michael Mallon said Banks, a Tottenham Hotspur supporter, showed up after drinking 16 pints of beer from Friday night into Saturday morning and never going to sleep.

Judge Emma Arthbuthnot, sitting at Westminster Magistrates' Court, told the defendant the incident had caused "public revulsion".

"The irony is rather than protecting the monuments you almost urinated on one. That was more by luck than judgement," she added.

"You showed no respect at the time for a man killed while protecting the Houses of Parliament."

The image of him urinating created an uproar and drew condemnation from members of parliament, including one who tried to save the officer's life by giving first aid.

Banks contacted the police after being recognised and confronted by his father, the court was told.

He was "ashamed of his actions", his lawyer Stuart Harris said.

While off duty and unarmed, Palmer died while stopping a knife-wilding assailant from entering parliament during the attack, when an assailant drove a car into pedestrians on the pavement. 

Khalid Masood, a British Muslim convert, killed Palmer and four pedestrians, and injured around 50 people. The attack ended when police shot the 52-year-old dead.