London: The Home Office’s backlog of 500,000 unresolved immigration and asylum cases will not be cleared for another 37 years at current rates of progress, according to a parliamentary watchdog.

Launching a report on the work of the now abolished UK Border Agency, Labour MP Keith Vaz, chair of the Commons home affairs select committee, warns that reforms of the organisation need to go beyond merely “rebranding”.

In taking evidence about UKBA’s work last year, the committee discovered an additional 190,000 cases in a “temporary and permanent migration pool”.

Vaz said: “The backlog of cases has now hit a staggering half a million people. This could fill Wembley stadium to capacity six times over. It has risen by 56 per cent in just three months. At the current rate it will take 37 years to clear and the Home Office cannot confirm that this is the last of the backlogs.”

The MP for Leicester East added: “Theresa May described the UK Border Agency as ‘closed, secretive and defensive’. However, despite abolition, nothing appears to have changed apart from the name. If people at the top are not replaced, this will only be an exercise in rebranding, as has happened in previous reincarnations. There should be no more bonuses paid to any senior Home Office managers until the backlogs are cleared.

“In evidence, the committee were told the immigration service would never be fixed. This is astonishing, since reducing immigration is a priority of this government. What the immigration service needs desperately is stability, the resources to clear the backlogs and a wholesale change in culture.”

The total of unresolved cases is said to stand at 502,462. Of those, more than 190,000 are deemed to be in the “migration refusal pool’’ those who have had their applications turned down. Many may have left Britain.

The report, published on Saturday, acknowledges that UKBA has had a “troubled history” but questions how ministers intend to prevent its problems “outliving its demise”. “The newly appointed directors general must have the ability and resources necessary to implement this change. The Home Office should outline exactly how they propose to bring about this change in culture.”

In March, May announced that UKBA was to be abolished. She told MPs that the agency “struggles with the volume of its casework” and that the number of illegal immigrants removed does not keep up with “the number of people who are here illegally”.

Sarah Rapson, the official temporarily in charge of visas and immigration pending the reorganisation, in effect told the committee that the problem would never be solved. The report says: “Asked if she thought the Immigration Service would ever be fixed she said: ‘I don’t think so’.

“The committee were surprised by this revelation. Although we welcome Ms Rapson’s honesty, the committee are concerned that the person tasked with ‘fixing’ the agency does not think the job will ever be complete.

“We are concerned this is an admission that Ms Rapson does not have the resources necessary to ‘fix’ the service.”

The Home Office should reveal the full scale of the backlog so it can apportion the funds necessary, the report says.