John Dickinson, one of the lawyers representing the Iraqis in the al-Sweady case, said the inquiry has taken so long to set up, because it was "vigorously opposed" by the MOD.
More than three years after it was ordered, the inquiry will examine claims that UK soldiers murdered 20 or more Iraqis, and tortured detainees in Maysan Province, southern Iraq, in May 2004.
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England have been beaten by nine wickets against Pakistan in the first Test at Lord's.
Mayor of London Sadiq Khan is backing the scheme.
Sunday will be a fine day across much of Scotland and northern England, with much less coastal mist and low cloud than yesterday.