Firms that run the government's controversial PIP disability tests have come under fire after it was revealed that they only employ four doctors between them.

The Personal Independence Payment, was introduced by the coalition government and is aimed at helping those with disabilities or long-term illnesses, but the tests that patients have to undergo to receive the payments have been long-criticised.

Atos and Capita are two firms who run the benefit checks, which has earned them more than £500m.

They have both been condemned for the way in which the checks are run and were grilled by MPs on the Work and Pensions Committee.

It came as 90,000 people overturned assessments that said they were not disabled enough for Personal Independence Payments with one MP saying that the tests had highlighted "basic factual errors" which included missing medical data.

The firm bosses admitted that they had repeatedly failed to meet the quality control target with 6.4% of PIP tests still deemed as "unacceptable."

The chief medical officer from Capita, Dr Ian Gargan revealed that out of 1,500 staff working at the firm's PIP division, just two were doctors.

However many do still come from a medical background, "Two thirds of our professionals have a nursing background and the remainder are from occupational therapy, physiotherapy and paramedicine," explained Gargan.

A similar situation was uncovered to be going on at Atos, which stunned some MPs.

The committee chair, Labour's Frank Field said: "You've got two doctors each, mega workload - maybe there's a lot of doctors out there who would long for some part-time work.

"You haven't sought them out to raise your game, have you?"

Dr Barrie McKillop, clinical director of Atos' PIP division said that their model was "strong" and that their staff brought expertise from different areas."

According to the most recent statistics from July 2017, the DWP say that around 3m people have registered to receive PIP support with the total number of claimants at 1.49m.