The legal battle is being waged by 17 families, including Rose Gentle, whose son, Gordon, 19, was killed by a roadside bomb in Basra in June last year, and Reg Keys, father of Tom Keys, one of six Redcaps killed by an Iraqi mob in June 2003.
Legal documents to be lodged at the court in London set out the case for a full independent inquiry into the legality of the war and the circumstances that led to the deaths of the soldiers. Lawyers for the families argue that under the Human Rights Act the Government has a duty to establish such an inquiry.
But ministers have refused the families' request, arguing that the war was legal. The families now intend to rely on the advice given by the Attorney General, Lord Goldsmith, to ministers in the run-up to the conflict. The Attorney General's advice was leaked to the media during this year's general election campaign.
The families want the inquiry to cross-examine the Prime Minister, the Attorney General, the Defence Secretary at the time, Geoff Hoon, and the Foreign Secretary, Jack Straw. They want the inquiry to establish why Lord Boyce, the former chief of defence staff, was given an unequivocal assurance that the war was legal.
Mrs Gentle said: "I now know that we are closer to establishing the truth about the war in Iraq and the dishonest way in which we were led to war."
Phil Shiner, of Public Interest Lawyers, representing the families, said he hoped the courts would hear the application for judicial review as quickly as possible. "Given the numbers involved and that the deaths occurred some considerable time ago, the families' lawyers will be requesting that the case be dealt with urgently," he said. "If that request is granted, there could be a hearing of this application before the end of 2005."
Last month, Mr Keys claimed that the London bombings were an "inevitable" consequence of the war. Mr Keys stood as an anti-war candidate in Tony Blair's Sedgefield constituency in the election. He said: "I've always been of the firm belief that you cannot go to a war at this scale [and] kill over 100,000 innocent civilians without there being a price to pay."
He called for a staged withdrawal from Iraq, and said there could be more attacks if it did not happen.
The case is being supported by the Stop the War Coalition and Military Families Against the War.