The company that carries out "fitness for work" tests on disabled benefit claims is seeking an early exit from its contract with the Government in the face of persistent death threats to staff.

Atos Healthcare said it had been in discussions with officials for "several months" about ending its £500 million work capability assessment contract, which is due to run to August 2015.

It was reported yesterday that the French-run company had recorded 163 incidents a month last year of members of the public assaulting or abusing its staff, in person and online.

Examples on Facebook were said to include: "murdering scum... won't be smiling when we come to hang you b******s".

The company has come under fire over the assessments - which are used to gauge eligibility for Employment and Support Allowance and Incapacity Benefit - amid claims people are being wrongly recommended for work.

A spokesman for Atos said it would not "walk away" from the contract.