A British Muslim man accused of raising funds for terrorism was punched, kicked and strangled during his arrest by specialist officers from the Metropolitan police, the high court in London heard today.

The court was told that Babar Ahmad, who is suing the police, was dragged from his bed and rammed against a window before being repeatedly beaten by officers dressed in riot gear during his arrest in December 2003.

During what his counsel Phillippa Kaufmann described as a "prolonged and violent series of gratuitous assaults" the 34-year-old IT support analyst claims officers forced him into the Muslim prayer position before shouting "Where is your God now? … Pray to him."

Kaufmann said: "The acts of the officers were ones of gross brutality, intended to humiliate and debase the claimant and to make him fear for his life. The officers engaged over a prolonged period in extreme, sadistic and dangerous acts of violence against an individual who was completely restrained and vulnerable.

"This was an extremely serious abuse of power which is in no sense justified, nor was it excusable on the grounds that it was perpetrated in the heat of an arrest for terrorism."

The Metropolitan police deny the claims and say that officers used reasonable force during the arrest at Ahmad's home in Tooting, south-west London. The court heard that the Met specifically denies that Ahmad was punched, controlled with handcuffs, stamped on or put in a dangerous neck hold.

Ahmad has been in detention since he was rearrested in 2004 following a request from the US government over claims that he had helped raise money to fund terrorist campaigns. Kaufmann said no evidence had been produced against Ahmad and he had never been charged with any offence.

Ahmad, who listened to proceedings via a video link, is awaiting a decision on whether his extradition to the US would contravene the European convention on human rights.

Before the raid in December 2003, officers were told Ahmad, then working as an IT analyst at Imperial College in London, was "potentially a very dangerous man" who was believed to have been trained in terrorist camps.

During the briefing, detectives compared him to Kamel Bourgass, who stabbed an anti-terror squad officer to death during a raid on a house in Manchester. Officers were told to use a strategy called "deck and dominate" during the arrest.

Kaufmann said that Ahmad adopted a "passive position" with his hands above his head as soon as the police entered the house.

"Between five and six officers then began to strike him all over his body. At some point, he asked them to stop but that had no effect," she said. "At another point, one officer grabbed his testicles and pulled them hard, causing him immense pain."

She said Ahmad was then thrown to the floor and dragged around by his handcuffs.

"The use of handcuffs was known by the officer to cause excruciating pain and one or more officers deliberately, repeatedly and sadistically used them for no reason other than to hurt the claimant," said Kaufmann.

She said that after being forced into the prayer position, Ahmad was bundled into the back of a police van where, she said, officers continued to punch and stamp on him before he was put in a neck hold.

"The neck hold is an extremely dangerous hold, as the officer would well have known," said Kaufmann. "It can only have been intended to cause the claimant to experience a state of utter terror, at the thought he was about to die."

Kaufmann said Ahmad first made his claims against the police the day after his arrest in 2003. A subsequent inquiry by the Independent Police Complaints Commission cleared the Met of any wrongdoing. Ahmad is due to give evidence at the high court on Wednesday .