A total of 1.6 million of the main disability benefit claims will be reviewed, with around 220,000 people expected to receive more money.

It comes after the DWP decided not to challenge a court ruling that said changes to PIP were unfair to people with mental health conditions.

The review could cost £3.7bn by 2023.

The minister for disabled people, Sarah Newton, said the DWP was embarking on a "complex exercise and of considerable scale".

She added: "Whilst we will be working at pace to complete this exercise it is important that we get it right."