Mr Corbyn has decided to impose only a one-line whip on his MPs for today’s vote on the SNP bid, meaning they are not obliged to attend, and could even back the former Scottish first minister Alex Salmond’s motion without fear of sanction.
Mr Salmond has drawn cross-party support for his motion calling on the Commons Public Administration and Constitutional Affairs Committee to probe any differences between Mr Blair’s public statements in the lead-up to the invasion, and private correspondence with then US president George Bush revealed by the Chilcot inquiry.
How to respond to the motion was reported to have caused ructions at the weekly meeting of Labour MPs, with some demanding a stringent three-line whip be imposed to emphasise the party’s opposition.
A source close to the Labour leadership said that Mr Corbyn expected MPs to oppose the motion.
Mr Salmond has accused the ex-prime minister of presenting misleading information to Parliament, and the motion notes the “contrast between private correspondence to the United States government and public statements to Parliament and people and also in the presentation of intelligence information”.
The SNP points to a note Mr Blair wrote to the US president in 2002 stating: “I’ll be with you, whatever,” as proof that he misled MPs about his intentions.
The motion calls on the parliamentary committee to “conduct a further specific examination of this contrast in public and private policy and of the presentation of intelligence”.
The motion is backed by the Greens, Plaid Cymru, Tory MP Sir David Amess, and Labour’s Kate Hoey.