LONDON, Dec 7 (AFP) - The United Kingdom government and the United States on Thursday (Dec 7) accused Russian security services of engaging in a sustained cyber-espionage campaign against top politicians, journalists and NGOs.

Russia has been suspected of meddling in UK politics before, including the divisive 2016 Brexit referendum, but the Conservative government has been criticised for failing to investigate.

In the latest claims, the foreign ministry said Russia's Federal Security Service (FSB) was behind "unsuccessful attempts to interfere in UK political processes" and said it had summoned Russia's ambassador to London about the issue.

US prosecutors meanwhile unsealed charges against two Russian nationals over the hacking of computer networks in Britain, the United States and other NATO countries. Those two men now face sanctions in both countries.

"Russia's attempts to interfere in UK politics are completely unacceptable and seek to threaten our democratic processes," UK Foreign Secretary David Cameron said in a statement.

"In sanctioning those responsible and summoning the Russian ambassador today, we are exposing their malign attempts at influence and shining a light on yet another example of how Russia chooses to operate on the global stage," he said.

Cameron's office said Centre 18, a unit within the FSB, was accountable for "a range of cyber espionage operations" targeting the UK.

One of the two men charged in the United States was an officer in that unit.

Photo from Reuters