The Inland Revenue has stopped pursuing more than £750 million of unpaid National Insurance contributions after attempts to recover the money failed.

In written answers to Norman Lamb, a Liberal Democrat member of the Treasury select committee, the government revealed that the Revenue has abandoned attempts to collect £789 million in contributions.

The figure covers unpaid contributions for the five years since the Revenue took over responsibility for collection.

Lamb said: “This is an awful lot of National Insurance that is legitimately due. The burden will fall on law-abiding taxpayers who pay their tax. I understand that some National Insurance has to be written off, but this figure is way too high.”