Data Breach hit US

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

The agency serves as the human resource department for the federal government.

US officials suspect that the cyber attack originated in China, according to a senior lawmaker.

The OPM issues security clearances and compiles records of all federal government employees.

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

The breach did not involve background checks and clearance investigations, officials said.

Senator Susan Collins, a member of the Senate Intelligence Committee called the breach "yet another indication of a foreign power probing successfully and focusing on what appears to be data that would identify people with security clearances."

'Perilously overdue'

Using a new cyber security system known as Einstein, the OPM detected a "cyber-intrusion" in April 2015. The FBI said it is investigating the breach.

Congressman Adam Schiff has called for cyber databases to be upgraded in light of the most recent attack.

Americans "expect that federal computer networks are maintained with state of the art defences", Mr Schiff said.

"The cyber threat from hackers, criminals, terrorists and state actors is one of the greatest challenges we face on a daily bases, and it's clear that a substantial improvement in our cyber databases and defences is perilously over