SAN FRANCISCO (Reuters) - Computer hardware maker Super Micro Computer Inc told customers on Tuesday that an outside investigations firm had found no evidence of any malicious hardware in its current or older-model motherboards.

In a letter to customers, the San Jose, California, company said it was not surprised by the result of the review it commissioned in October after a Bloomberg article reported that spies for the Chinese government had tainted Super Micro equipment to eavesdrop on its clients.

Super Micro had denied the allegations made in the report.

A person familiar with the analysis told Reuters it had been conducted by global firm Nardello & Co and that customers could ask for more detail on that company’s findings.

Nardello tested samples of motherboards in current production and versions that were sold to Apple Inc and Amazon.com Inc, which were both named in the article, the person said.

It also examined software and design files without finding any unauthorized components or signals being sent out.

He said the company was still reviewing its legal options.

Apple, Amazon and U.S. and U.K. officials have all said they have no knowledge of any hardware attacks via Super Micro.