The International Criminal Court has been asked to investigate the actions of former members of the British cabinet and troops over allegations of "systematic torture" in Iraq.
The European Centre for Constitutional Human Rights, based in Germany, and the Public Interest Lawyers firm, based in England, said in a statement that they had jointly filed a complaint to the ICC.
The complaint called for the "opening of an investigation" into the actions of senior British officials "in particular the former minister of defence Geoff Hoon and secretary of state, Adam Ingram, for systematic torture and abuse of prisoners in Iraq between 2003 and 2008."
More than 400 Iraqi prisoners have contacted PIL in the past few years, alleging "serious abuse and humiliation" on the part of British soldiers, the two organisations said.
"Our legal team has exhausted all legal avenues" to obtain justice in Britain, said Phil Shiner, a public interest lawyer.
A 250-page document was handed over to the ICC, comprising 85 particularly representative cases and more than 2,000 accusations of abuse documented over five years, said the two organisations.
A similar complaint to the ICC failed in 2006. However, "eight years later, it is evident that a thorough investigation was and is remains necessary," read the joint statement.
Serious violations of the Geneva Convention which protects prisoners of war from abuse may constitute a war crime.
According to the Sueddeutsche Zeitung, the British ministry of defence admitted "isolated cases" of abuse by British soldiers in Iraq, but denied anything systemic.