{{show_title_date || "China bashes US allegations of cyber-attacks, 6/5/15, 4:48 PM ET"}}

Second cyberattack on US may have exposed security information

A second cyberattack on the federal government has been discovered that could have accessed investigations for security clearances and other job background checks, an administration official said Friday.

The second hack was discovered as officials investigated the first cyberattack on the Office of Personnel Management that exposed as many as 4.2 million current and former federal employees.

The second breach likely involved information submitted on a form called the Standard Form 86, in which department applicants disclose information such as their social security number, psychological health and information on relatives, officials said.

RELATED: Lindsey Graham blames President Obama for data breach

A U.S. official familiar with the cyberattack said hackers, suspected to be linked to the Chinese government, “may have gained access to some” of that information, but how much is not yet clear.

China has denied any involvement in the cyberattack and last week accused the U.S. of making “groundless accusations.”

The U.S. official said that the Chinese strategy is to “vacuum up everything.”

“They have the bodies, the people who do this,” the official said. But “we are still talking about manageable risk,” the official said.

The breach of OPM data is considered to be the largest cyberattack in U.S. history, and the office has said around 4.2 million current and former federal workers may have had their personal information compromised.

This article originally appeared at NBCNews.com