Hackers in China are suspected of conducting a massive data breach in the US, compromising the personal information of millions of government employees.
The US Office of Personnel Management (OPM) revealed that more than four million current and former federal employees have been affected.
The OPM detected a cyber-intrusion in April this year affecting its information technology systems and data. The breach was identified when the agency started working to enhance its security control.
The agency is offering credit monitoring and identity theft protection for the affected employees. The notifications will be sent between the 8th and 19th of this month.
OPM director Katherine Archuleta said: "We take very seriously our responsibility to secure the information stored in our systems, and in coordination with our agency partners, our experienced team is constantly identifying opportunities to further protect the data with which we are entrusted."
The US Department of Homeland Security’s Computer Emergency Readiness Team (US-CERT) and the Federal Bureau of Investigation (FBI) are investigating the full impact of the attack.
FBI said: "We take all potential threats to public and private sector systems seriously and will continue to investigate and hold accountable those who pose a threat in cyberspace."
Though OPM’s statement did not provide details about the source of the breach but the American Federation of Government Employees (AFGE) said it may have come during a Chinese cyberattack in April.
American Federation of Government Employees national president J. David Cox Sr said in a statement: "This evening we learned that the personal information of all 2.1 million current federal employees and an additional 2 million federal retirees and former federal employees may have been compromised during a Chinese cyberattack in April.
"The attack targeted personnel records of federal employees and retirees maintained on computers by the Office of Personnel Management."
The latest data breach is the second on the OPM systems. Last July, the government unveiled an attack at the agency’s computer systems by Chinese hackers.
The US has recently urged China to investigate reports that indicate China redirected internet traffic and used information for attacking American websites.
In April 2013, the US and China have agreed to work together on cyber security after accusing each other of hacking and Internet theft.
