Two U.S. senators have sent a letter to Super Micro Computer Inc. asking if and when the company found evidence of tampering with hardware components after a news report described how China's intelligence services used subcontractors to plant malicious chips in the company's server motherboards.

Florida Republican Marco Rubio and Connecticut Democrat Richard Blumenthal on Tuesday gave the company until Oct. 17 to respond to a list of questions that also included whether the company had investigated its supply chain and cooperated with U.S. law enforcement.

In the Bloomberg Businessweek's report, one official was reported as having said investigators found that Chinese infiltration through Super Micro had reached almost 30 companies, including Amazon.com Inc. and Apple Inc. Super Micro and both Amazon and Apple disputed the findings. The U.S. Department of Homeland Security said it has "no reason to doubt" the companies' denials of the reporting.