Jeremy Corbyn has signalled he will keep fighting the renewal of Trident by becoming a vice-president of the campaign for nuclear disarmament, PA reported.
Although he will step down from another role in the campaign after becoming Labour leader, Corbyn will take on a new position reflecting his "lifelong commitment" to nuclear disarmament, the CND said.
His views are at odds with his party's own policy to support renewing the nuclear weapons system, which remained in place at the recent Labour conference.
Corbyn will continue to be part of the CND
The veteran MP has been opposed to nuclear weapons throughout his career and has been vice-chair of CND, which campaigns for unilateral disarmament by the UK, for many years. He joined CND as a teenager in 1966.
He is facing a major split in Labour over whether Britain's nuclear deterrent should be replaced, with a crunch Commons vote due in the coming months.
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CND said that while Mr Corbyn was stepping down as vice-chair in recognition of his increased workload as leader of the opposition, he would take on the role of vice-president instead. "He didn't want to resign from CND, so he decided to accept a vice president role," a spokesman said.
BBC political correspondent Carole Walker said Mr Corbyn's new role was likely to increase tensions within his party: "Privately some are deeply concerned at the uncertainty over Labour's position on such a key issue."
A 2002 picture of the Royal Navy's 16,000 ton Trident-class nuclear submarine, Vanguard
Mr Corbyn was rebuked by colleagues last month for undermining the internal debate after bluntly stating that there were no circumstances under which he would authorise use of the weapons.
He had been due to address the CND conference in London this weekend, but he is now said to have other engagements.
General secretary of CND Kate Hudson said: "This is a fitting tribute to a very principled man with a lifelong commitment to CND and the cause of nuclear disarmament.
"Working together, with enormous support from across society, we will prevail against Trident and secure a crucial step towards global disarmament."