James Clapper, US director of national intelligence, said China was "the leading suspect" behind the breach affecting personal data of millions of US government employees, which was revealed earlier this month.
Chinese foreign ministry spokesman Lu Kang responded: "We have noticed that the US is still investigating, but feels that China is responsible. This is absurd logic.
"We understand this as showing the US has adopted the presumption of guilt rather than the presumption of innocence," he added at a regular briefing.
Cybersecurity specialists said the breach of data on at least four million current and former federal employees appeared to be part of an effort to build a database for espionage.
More From This Section
Soon after the breach was made public, US officials told media they believed China was involved. Beijing rebuffed the claims as "unscientific".
The US Office of Personnel Management said that employees, retirees, contractors and job applicants may have had their personal information compromised in the breach.
Facing an outcry from employees and lawmakers, the US administration has announced new steps to boost the security of its online records, including in some parts that still use decades-old technology.