US government investigators have discovered a separate attack on the federal Office of Personnel Management (OPM) targeting sensitive information about government employees similar to a hacking incident revealed last week, a senior US official has said.

US investigators also suspect a Chinese link to the attack, a source familiar with the probe told Reuters on Friday.

Associated Press reported that hackers appear to have gained access to sensitive background information submitted by US intelligence and military personnel for security clearances that could potentially expose them to blackmail.

It said a form authorities believed to have been accessed, Standard Form 86, required applicants to fill out deeply personal information about mental illnesses, drug and alcohol use, past arrests and bankruptcies.

The form also required the listing of contacts and relatives, potentially exposing any foreign relatives of US intelligence employees to coercion, the report said. The form also required the applicant's Social Security number and that of their cohabitant.

White House spokesman Josh Earnest said the investigation continued into last week’s OPM breach that the government said affected up to 4 million federal employees.

Source: Reuters And AP