British cybersecurity experts have warned U.K. government agencies not to use antivirus software produced by the Russian firm Kaspersky Lab.

The head of the National Cyber Security Center, Ciaran Martin, said in a letter dated December 1 that "Russia is acting against the U.K.'s national interest in cyberspace."

He cautioned that "a Russia-based provider should never be used" for the security of vital systems.

The statement stopped short of urging the public to stop using Kaspersky products.

In September, the U.S. government barred agencies from using Kaspersky products after expressing concern that the company could have links to the Russian government or Russian spy agencies.

In October, media reports linked a theft of information from the U.S. National Security Agency (NSA) to Kaspersky software.

Kaspersky has denied any wrongdoing and has said it has no secret collaboration with Russian security agencies.

Based on reporting by AP and Reuters