The U.S. Department of Homeland Security said on Saturday it currently had no reason to doubt statements from companies that have denied a Bloomberg report that their supply chains were compromised by malicious computer chips inserted by Chinese intelligence services.

"The Department of Homeland Security is aware of the media reports of a technology supply chain compromise," DHS said in a statement.

"Like our partners in the UK, the National Cyber Security Centre, at this time we have no reason to doubt the statements from the companies named in the story," it said.

Bloomberg Businessweek on Thursday cited 17 unidentified intelligence and company sources as saying that Chinese spies had placed computer chips inside equipment used by around 30 companies, as well as multiple U.S. government agencies, which would give Beijing secret access to internal networks.

Britain's national cyber security agency said on Friday it had no reason to doubt the assessments made by Apple and Amazon.com challenging the report.

Apple contested the Bloomberg report on Thursday, saying its own internal investigations found no evidence to support the story's claims and that neither the company, nor its contacts in law enforcement, were aware of any investigation by the FBI on the matter.

Apple's recently retired general counsel, Bruce Sewell, told Reuters he called the FBI's then-general counsel, James Baker, last year after being told by Bloomberg of an open investigation of Super Micro Computer, a hardware maker whose products Bloomberg said were implanted with malicious Chinese chips.

"I got on the phone with him personally and said, 'Do you know anything about this?," Sewell said of his conversation with Baker. "He said, 'I've never heard of this, but give me 24 hours to make sure.' He called me back 24 hours later and said 'Nobody here knows what this story is about.'"

Baker and the FBI declined to comment on Friday.