Shadow business secretary Chuka Umunna has called for Labour to unite behind the new party leader in an apparent offer of reconciliation from the party's modernising wing to leadership favourite Jeremy Corbyn.
He also welcomed a surge in party membership and support in the run up to the leadership contest saying that it was important not to "dismiss out of hand" criticism of New Labour.
Former foreign secretary Jack Straw has dismissed Jeremy Corbyn's pledge to apologise for the Iraq War on behalf of Labour if elected as the party's leader.
Mr Corbyn, the front runner in the leadership race who fiercely opposed the 2003 invasion, said the party must say sorry for the "deception" in a statement to The Guardian.
Mr Straw, who helped to lead the case for war and has always defended the controversial decision to invade, told ITV News: "There was no deception."
"I deeply regret the loss of life," Mr Straw added.
British-based group the Iraq Body Count has recorded 142,856 to 162,136 civilian deaths in Iraq from violence following the 2003 invasion as part of a total death toll of 219,000, though all figures are considered to be low-end estimates. Some 179 British personnel died in the conflict.
The Chilcot Inquiry, which was set up in July 2009 to look at the UK's role in the Iraq War, including the decision to invade and the preparation of troops, is still to publish its findings.
Labour's Chuka Umunna urged his party to unite around its new leader in an apparent offer of reconciliation to left-winger Jeremy Corbyn.
Some 3,000 infiltrators have been discovered and barred from voting in the Labour leadership contest, a party source has told ITV News.
The Labour leadership candidates will meet with acting leader Harriet Harman after accusations the vote was infiltrated by opponents.