THE Ministry of Defence has been hacked by China with the cyberattack causing a massive data breach, according to reports.
MPs will be informed on Tuesday of the attack which targeted service personnel.
While the Government will not reveal the country behind it, Sky News says it understands this is China.
Beijing is thought to be accused of two or three attempts to hack MoD employees.
The attack is thought to have been carried out on a payroll system which included current service personnel, some officials and some veterans.
Mostly names and bank details have been exposed, the report said.
All salaries will be paid this month.
The contractor system attacked is not connected to the main MoD computer systems and had been taken down while a review is carried out.
The MoD is said to be assessing the scale of the hack.
The news comes less than two months after China's "state-affiliated actors" were blamed by the Government for two "malicious" cyberattack campaigns in the UK.
Deputy Prime Minister Oliver Dowden told the Commons two incidents involved an attack on the Electoral Commission - responsible for overseeing elections and political finance - in 2021, and targeted attacks against China-sceptic MPs.
