Rishi Sunak will be urged to apologise to veterans who were kicked out of the armed forces for being gay.
While homosexuality was decriminalised in 1967, anyone found to be gay in the UK military before 2000 faced being booted out.
Thousands were jailed or dismissed and many were outed to their families and friends against their will.
Marking Pride Month, Labour frontbenchers will today step up calls for the Prime Minister to issue a formal apology.
The demand comes amid fears a review by Lord Etherton into the treatment of gay people in the Army, RAF and Royal Navy in the decades before 2000 may be delayed.
Writing exclusively for the Mirror, Shadow Equalities Secretary Anneliese Dodds and Shadow Defence Minister Rachel Hopkins say publishing and acting on the review would begin the healing process.
Ms Hopkins said: “Many LGBT+ veterans have shown enormous courage to share traumatic experiences with Lord Etherton’s review. The PM should now show some courage by publishing the review and apologising on behalf of the Government.”
Lord Etherton was appointed to lead the inquiry in June 2022, though sources say no date was set for the review’s publication.
He was the first openly gay judge in the senior courts, entering into a civil partnership in 2006. He married his partner in 2014.
A Government spokeswoman said Lord Etherton had now concluded his review and added: “We will carefully consider the findings and respond in due course.”
A Cabinet Office spokeswoman said: “There is no delay to either the publication of the report [or] the response.”