Payroll data at risk includes names, bank details and addresses of current and former force members, government sources suggest

An estimated 270,000 payroll records belonging to nearly all members of Britain’s armed forces have been exposed to Chinese hackers in a breach at a third-party contractor that was discovered a few days ago.

The data at risk includes names and bank details and, in a few thousand instances, addresses and national insurance numbers of current and recently departed members of the army, navy and air force and reservists, government sources indicated.

There is no immediate evidence that any data has been stolen or interfered with, but inquiries are continuing. Personnel are expected to be offered credit checks so people can monitor if their bank details have been used without permission.

Grant Shapps, the UK defence secretary, is expected to brief MPs on Tuesday afternoon on the situation and the steps being taken by the MoD to deal with the problem. Hackers are believed to have been present in the system for some time, possibly weeks.