Jeremy Corbyn is set to use his first conference speech as Labour leader to apologise on behalf of his party for taking Britain into war in Iraq.

In a sign of how Mr Corbyn wants to reshape the public’s view of the party under his leadership, he is expected to say that Labour has learnt its lesson from the conflict and will “never make the same mistake again”.

He will add that in future Britain’s role in international affairs needs to change to the promotion of conflict resolution and co-operation rather than using UK forces to achieve regime change.

An apology will delight Labour activists and be welcomed by some senior members of the parliamentary party who hope it will pre-empt criticisms of former ministers when the Chilcot inquiry finally reports later this year.

“We are urging him to make the apology in his speech. It would be surprising if he did not take the opportunity to do it on Tuesday,” said one Labour MP who supports Mr Corbyn.

But the move will cause disquiet among some in the centre of the party who fear it will reinforce public perceptions that Labour are “soft” on national security. That view is likely to be re-enforced if, as expected, the party decides to hold an emergency debate on whether Labour should support the renewal of Trident during the conference.

Mr Corbyn indicated that he would support a move to debate the issue and has long advocated unilaterally scrapping Britain independent nuclear deterrent.

He has suggested that scrapping Trident would become official policy if a resolution to that effect is passed.

HMS Victorious, a Trident nuclear submarine, patrols the waters of the west coast of Scotland (Andy Buchanan/AFP/Getty Images)

Mr Corbyn indicated during his campaign for the leadership that he would make the symbolic apology for the invasion of Iraq should he win.

“It is past time that Labour apologised to the British people for taking them into the Iraq war on the basis of deception and to the Iraqi people for the suffering we have helped cause,” he said.

“The endless delay on the Chilcot inquiry is wrong. But we don’t have to wait for Chilcot to know that mistakes were made,” Mr Corbyn said.

Mr Corbyn’s team hopes his first conference will showcase what it describes as the “three pillars” of his leadership: a new approach to the economy based on growth rather than austerity; political reform that engages voters “more directly” and a changed approach to foreign affairs.