Ciaran Martin, head of the National Cyber Security Centre, wrote  to civil service chief saying that Russia is acting against the U.K.’s national interest in cyberspace.

Russia seeks “to target UK central government and the UK’s critical national infrastructure" and that "any Russian provider should never be used” for systems that deal with issues related to national security.

The agency said it’s not advising the public at large against using Kaspersky’s popular antivirus products.

Martin says British authorities are holding talks with Kaspersky about developing checks to prevent the “transfer of UK data to the Russian state”.

Kaspersky has denied wrongdoing and says it doesn’t assist Russian cyberespionage efforts.

In September, the US government barred federal agencies from using Kaspersky products because of concerns about the company’s ties to the Kremlin and Russian spy operations.

News reports have since linked Kaspersky software to an alleged theft of cybersecurity information from the US National Security Agency. Britain has issued increasingly strong warnings about Russia’s online activity. Martin said last month that Russian hackers had targeted the UK’s media, telecommunications and energy sectors in the past year.

US authorities are investigating alleged Russian meddling in the 2016 presidential election, and some British lawmakers have called for a similar probe into the U.K.’s European Union membership referendum.

Prime Minister Theresa May said last month that Russia was “weaponising information” and meddling in elections to undermine the international order.