In response, the Ministry of Defence said European human rights laws had applied in Musa's case and that a court-martial over his death earlier this year, which found one soldier guilty of unlawful conduct, had been sufficient. "The court-martial was a thorough and effective investigation into the circumstances of Mr Musa's death and we maintain there has not been a procedural breach," a spokesman said. "The House of Lords did not call for a public inquiry."

The government had maintained that soldiers serving in Iraq should not necessarily be subject to Britain's Human Rights Act or the European Convention on Human Rights because they were operating in conflict in a foreign country.

The lords' ruling made clear, at least in the case of Baha Musa, that the legislation did apply to soldiers serving on British bases in Iraq or holding detainees in their custody. Human rights campaigners were elated by the decision, which they said held the government to account and meant any British detention facility anywhere in the world was now covered.

"Our law lords have today ensured that there can never be a British Guantanamo anywhere in the world ... there can be no British detention facility where the law does not apply," said Shami Chakrabarti of rights group Liberty.

"Individual soldiers cannot be scapegoated, cannot be left anymore to carry the can for the failures of our government and the military high command." Separate cases also involving deaths in Iraq and also before the House of Lords on Wednesday were rejected. Shiner, who also brought those cases, said he would now appeal to the European Court of Human Rights in Strasbourg.

Musa, 26 when he died, was detained with several other Iraqis when British troops raided a hotel in the southern city of Basra. Those held were kept blindfolded, put in stress positions and beaten during 36 hours of detention, the court martial held earlier this year heard. Musa died after suffering 93 injuries, including broken ribs and a broken nose. A personal injury lawyer is involved in bringing a separate case to the High Court seeking to sue the Ministry of Defence for punitive damages for his injuries.