A top US security official has accused China of being a leading suspect behind the recent hacking of millions of records and background information from the U.S. Office of Personnel Management.

Director of National Intelligence, James Clapper, said Thursday that the Chinese government was responsible for the massive breach of federal government data announced on June 4, according to the Wall Street Journal.

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Clapper added the breach, which may have rendered over 17 million social security numbers compromised, was very difficult to achieve and as such "You have to kind of salute the Chinese for what they did."

Reports indicate that Clapper's remarks, the first public cyber-attack accusation from a high-ranking U.S. official against Beijing, was made during an intelligence conference held in Washington DC.

"China remains the leading suspect," Clapped said."The U.S. government continues to investigate."

The statement accusing Chinese hackers of the massive data breach comes only three days after high-ranking US-China talks which saw both super-powers working to reach an agreement on a "code of conduct" in cyberspace.

U.S. Secretary of State John Kerry said on Wednesday that "whether or not it was sanctioned by government, or whether it was hackers, or individuals, the government has the ability to prosecute."

He stressed the importance of the agreement reached with China on the development of a "code of conduct" for states in cyber security.

Clapper also revealed that high-ranking U.S. officials are torn as they continue to debate on the way forward - on how they should respond in retaliation for China's alleged massive breach.

White House spokesman Josh Earnest has given an insight into the nature of the response in consideration. "If there is a response, it's probably not one we are likely to telegraph in advance," He said on Thursday.

High-ranking U.S. officials certainly have the power to impose sanctions against those responsible for the attacks. In April, President Barrack Obama signed an executive order which authorizes the Treasury Department to place sanctions on persons and organizations conducting cyber attacks that significantly threatens the U.S. government and companies.

Clapper said hackers would continue to be a threat to the government and American firms until policy makers create a strong psychology of deterrence against those found responsible.

"The challenge here, the problem for us, frankly, is until such time as we can create both the substance and the psychology of deterrence, this is going to go on," he said. "And there's been frankly a struggle for us, because of concerns about unintended consequences and other related policy issues."

Meanwhile, China insists on its innocence in the OPM data breach. Chinese senior diplomat and State Councilor Yang Jiechi has branded the accusations as "irresponsible and unscientific."

TagsOPM data breach, OPM hack, US-China relations