A Pakistani citizen who says he was tortured over a period of 10 years after being captured by UK special forces in Iraq and handed over to US troops will on Wednesday contest the government’s claim that he cannot pursue his case on the grounds that it would damage Britain’s relations with America.

Yunus Rahmatullah was seized in Iraq in 2004 in an incident that was kept secret from ministers and only disclosed to MPs five years later. Rahmatullah, now 31, was released by the US without charge in May and is seeking to sue the Ministry of Defence and the Foreign Office, accusing them of responsibility for his subjection to torture and abuse.

The MoD and the Foreign Office claim that if the high court allows the case to go ahead, the UK’s defence and security relationship with the US would be seriously harmed. British government lawyers argue that the “act of state” doctrine means that a British court cannot question the activities of US troops.

Government lawyers have used the same argument to prevent Abdel Hakim Belhaj, a prominent Libyan dissident, and his wife from suing the former foreign secretary Jack Straw and MI6 over the couple’s abduction and subsequent rendition to Tripoli.

The lawyers argue that British courts cannot hear the Libyan case since any wrongdoing involved the CIA in activities abroad as well as the British government.

Rahmutallah is believed to have been first held at Camp Nama, a secret detention facility at Baghdad airport that British troops helped to run. He was later transferred to Iraq’s notorious Abu Ghraib jail before being rendered to the Bagram “black prison” in Afghanistan.

Last year the UK supreme court described Rahmatullah’s treatment by UK and US forces as unlawful and a possible war crime. “The, presumably forcible, transfer of Mr Rahmatullah from Iraq to Afghanistan is, at least prima facie, a breach of article 49 [of the fourth Geneva convention],” it said. But the court agreed with the UK government that it was unable to enforce his release.

Kat Craig, legal director of the charity Reprieve, told the Guardian: “Yunus Rahmatullah faced 10 years of unlawful detention without charge, trial or explanation. Now that he has finally been reunited with his family, he wants answers. He wants to know why he was subjected to horrific torture by the Brits, and why was he then handed over to the US to face the unimaginable terror of Abu Ghraib before being rendered to Afghanistan.

“The British government is drawing out Yunus’s ordeal and trying to hold itself above the law. At the crux of the government’s argument is the assertion that, providing British operatives commit terrible wrongs alongside their American counterparts, they can never be held to account. The UK government must not be allowed to hide behind the coattails of the US to cover up its wrongdoing.”

Rahmatullah describes in detail his torture and abuse in a 60-page court document. He says when he was captured by British special forces in Iraq in early 2004 he was beaten unconscious. Soldiers cut his clothes with a pair of scissors until, he says, he was completely naked.

His lawyers’ statement of claim describes how a soldier poured water on Rahmatullah’s face after placing a cloth over his mouth and nose, causing “a sensation of drowning”. He was shackled and hooded, and lapsed in and out of consciousness as he was beaten and thrown against a wall. He was suspended upside down and repeatedly dunked into a tank of water, says the court document.