Thousands of asylum seekers will be sent Home Office questionnaires which could be used to decide their claims in a bid to cut the soaring backlog of cases.

It is understood about 12,000 people from Afghanistan, Syria, Eritrea, Libya and Yemen, who have applied for asylum in the UK and are waiting for a decision, are understood to be eligible under the policy being launched on Thursday.

The Home Office announced the plans, which aim to speed up processing applications for people from nations that typically have a high grant rate in the UK of more than 95%, as figures due to be published are expected to show there are more than 150,000 outstanding asylum cases.

It comes after Prime Minister Rishi Sunak pledged to reduce the asylum backlog by the end of the year as he vowed to “stop the boats” crossing the Channel. The Home Office is faced with having about 10 months to clear 92,601 initial asylum claims which were in the system as of the end of June 2022.

Asylum seekers subject to the process, which applies to adult applicants and their child dependants but not lone migrants under the age of 18, will not be automatically interviewed.

Instead, they will be sent a 10-page questionnaire to fill out, containing about 40 questions which may not all apply to them, and asked to return it within an initial 20 working days before being offered an extension.

Some campaigners criticised the plans as “clumsy” amid reports that asylum seekers will be told to fill out the form in English. Others welcomed efforts to reduce the backlog but said the approach could throw up more “bureaucratic hurdles”.

A Home Office letter published on Twitter by Sky News, which was addressed to “stakeholders” and set out the plans, warned asylum seekers risked having their claim “withdrawn” if they failed to return the questionnaire without a “reasonable explanation”.

Applicants could still be called for an interview and any who do not provide the required information and evidence could have their claim rejected.

Those granted asylum will be allowed to work and would then be expected to find their own accommodation.

Officials insisted the move was not akin to a so-called asylum amnesty and stressed thorough security checks would still be carried out.

Caitlin Boswell, from the Joint Council for the Welfare of Immigrants (JCWI), said: “People fleeing conflict and violence clearly need this Government to make quicker and fairer asylum decisions, but this latest move from Government is clumsy, unthinking and could put people’s safety at risk.

“No-one’s right to refuge should be jeopardised because they weren’t able to fill in a long unwieldy form in a language they don’t speak. This Government shouldn’t be cutting corners when it comes to making life-changing decisions on people’s futures.”

The Refugee Council’s chief executive, Enver Solomon, said moves to reduce the backlog were “welcome but the answer is not yet more bureaucratic hurdles and threats of applications being withdrawn”, adding the process should be “well thought-out”.

“As it stands, the Prime Minister will fail to meet his commitment to clear the backlog by the end of this year and, if he is serious about it, there must be a more ambitious, workable, person-centred approach that sees the face behind the case.

“A priority should be accelerating the asylum claims of thousands of unaccompanied children and those of the 10,000 people who have been waiting for more than three years, as well as making quick positive decisions for those from countries like Sudan and Iran that also have very high grant rates.

“Without these steps, the record backlog is only going to continue to grow, at great human and financial cost,” he said.

The British Red Cross’s Christina Marriott raised concerns that a 20-day time limit could have “devastating impacts”.

“These men, women and children are from places like Afghanistan, Syria and Iran, they may not speak English and are likely traumatised from fleeing persecution and war. They need our support and compassion, not rushed and complicated bureaucracy that will only increase suffering,” she said.

“We know from experience that government communications with people seeking asylum often falls short – translations are rarely provided and forms are lost in transit. This time limit could have devastating impacts on people who need protection, whilst creating more work for the Home Office.”

Labour’s shadow home secretary, Yvette Cooper, said: “It’s damning that the Home Office isn’t doing this already, given Labour has been calling for the fast-tracking of cases – including for safe countries like Albania – for months and the UNHCR recommended it two years ago.

“Meanwhile, the asylum backlog has skyrocketed – up by 50% since Rishi Sunak promised to clear it.

“After 13 years of Government, the Conservatives clearly have no idea how to fix the mess they have made of the asylum system.”

The latest available Home Office figures, published in November, showed more than 140,000 asylum seekers were waiting for a decision on their claim after the backlog of applications soared by over 20,000 in three months.

In the year to September 2022, there were 143,377 asylum applications which were yet to be determined, of which 97,717 had been waiting for over six months.

This was at least three times higher than the 45,255 applications awaiting an initial decision at the same period in 2019, when 26,125 had been waiting for more than six months.

The numbers are expected to continue to rise. The latest official data is due to be published on Thursday.