The government will attempt to push back a legally binding deadline for the completion of an independent review of Prevent, the programme that aims to stop people becoming terrorists, the Guardian understands.

Communities, activists and civil liberties organisations have been calling for a review of Prevent for years, claiming it fosters discrimination against people of Muslim faith or background. Advocates of the strategy reject this and say it has successfully diverted vulnerable individuals from being radicalised.

The review was first announced in January 2019 and it was written into the Counter-Terrorism and Border Security Act along with a statutory requirement for it to report back to parliament by August this year.

In December its chair Lord Carlile was forced to step down from the role amid questions over his impartiality towards the strategy, throwing the future of the review into doubt.

On Monday, four months after Carlile’s departure, the Home Office launched a recruitment campaign for a new chair, with applications welcome till 1 June, and the Guardian understands the government intends to extend the deadline for the completion of the review.

A Home Office spokesperson said: “This review presents a valuable opportunity and it is important that the new reviewer has sufficient time to complete it. We are aware that this is likely to have implications for the existing timescale and are taking steps to address this. More details will be provided to parliament at the earliest opportunity.”

The most controversial element of the Prevent programme is the statutory duty imposed on schools, NHS trusts, prisons, local authorities and other public bodies to report concerns about people they suspect may be at risk of turning to extremism.

Muslims groups have made it clear they have little or no confidence in Prevent, which over time has faced claims that it is more concerned with gathering intelligence than supporting communities.

Harun Khan, the secretary general of the Muslim Council of Britain, said: “The UK government must learn from its past mistakes and ensure that the upcoming review is effective, wide-ranging and transparent, and that the reviewer is an individual who is truly independent.

“This extension request must not be a case of the review being kicked into the long grass to avoid scrutiny. Prevent has caused untold damage, not least to British Muslim communities. A review into Prevent is long overdue already and it is imperative that it takes place as a matter of urgency, and the individual tasked with its implementation has the independence, credibility and trust required to deliver it.”

Carlile’s appointment as chair in August 2019 was immediately criticised as it emerged he had previously told parliament he “may be somewhat biased towards” the strategy and had declared his “considered and strong support” for the programme.

Rights Watch UK, a human rights charity, filed a legal challenge and Carlile was removed before the case came to court.

Launching the recruitment campaign on Monday, the security minister, James Brokenshire, said: “Prevent gives vulnerable people the support they need to protect them from terrorist recruiters. We are always looking at how we can make the programme more effective, which is why we are committed to this independent review. I look forward to the appointment of the reviewer so they can get on with their vital work.”

The shadow home secretary, Nick Thomas-Symonds, said: “The government is clearly falling behind on the independent review of the Prevent programme, which was supposed to be completed by August 2020. It is disappointing to see yet more time wasted.

“The government must move quickly in appointing a new chair for this important project. Not least because we know there are serious concerns that some will seek to use the current crisis and period of isolation, as an opportunity to promote online violent extremism.”

Rosalind Comyn, a policy and campaigns officer at the campaign group Liberty, said: “The government has had more than a year to organise a review of the Prevent strategy, but stark failings like appointing a biased reviewer have left the process flawed from the start.

“Prevent is embedding discrimination in our public services and damaging lives, with Muslims and people of colour bearing the brunt of its impact. The delay and failings surrounding the review have shattered any trust communities had in this process and the government’s commitment to listening to their concerns. It’s time for ministers to stop dragging their heels and give the Prevent strategy the robust, independent scrutiny it so desperately needs.”