Data breach affects millions of US government workers

Chinese hackers are suspected of carrying out a "massive breach" affecting the data of millions of US government workers, officials said.

The Office of Personnel Management (OPM) confirmed on Thursday that almost four million current and past employees have been affected.

OPM serves as the human resource department for the federal government. The agency issues security clearances and compiles records of all federal government employees.

Information stored on OPM databases includes employee job assignments, performance reviews and training, according to officials.

The breach did not involve background checks and clearance investigations, officials said, but could potentially affect every federal agency.

Susan Collins, a member of the Senate Intelligence Committee, said it was thought to have originated in China.

The Chinese embassy in Washington warned against "jumping to conclusions". Embassy spokesman Zhu Haiquan told Reuters news agency that the accusations were "not responsible, and counterproductive".