MOSCOW (REUTERS) - Russian President Vladimir Putin said on Thursday (Dec 20) that British Prime Minister Theresa May had no choice but to implement Brexit and steer clear of a second referendum or risk undermining faith in British democracy.

Putin's comments, made at his annual news conference, are likely to irk some British politicians who have suggested Russia may have meddled in the 2016 Brexit referendum because it wants to weaken the European Union and the West.

Russia has flatly denied that allegation and said it favours a strong EU.

Putin on Thursday said Brexit was a matter for the British people and that London would accuse him of something if he commented on the matter, but that he thought May did not have any choice but to deliver Brexit.

"In terms of Brexit, if it is carried through to the end, I can understand the position of the prime minister who is fighting for Brexit ... There was a referendum after all. What can she do? She must enact the will of the people, expressed during the referendum."

Putin said holding another referendum was risky.

"Is that democracy or what? What will critics of this process say if and when they spit on Brexit and hold more referendums until such time as somebody is not unhappy. What then would a referendum be for?"

With just under 100 days until Britain is due to leave the EU on March 29, deep divisions in parliament have raised the chances of leaving without a deal and increased calls for a second referendum to break the deadlock.

Putin, who said Russia's own relations with Britain were deadlocked but that Moscow was interested in improving them, characterised Brexit as an example where Western democracy was starting to show cracks.

"Brexit happened," he said. "(But) nobody wants to implement it. They aren't recognising the results of elections. Democratic procedures are being degraded, destroyed, their value is being destroyed."

Putin also held up opposition to the election of US President Donald Trump as evidence that democratic processes in the West were fraying.

Trump's foes have called for his impeachment and Special Counsel Robert Mueller is investigating allegations of collusion with Russia.

Putin cast the opposition to Trump as a symptom of "deep, tectonic changes" underway in what he described as the Anglo-Saxon world.

"Trump won - this is an obvious fact and no one disputes this, but they don't want to recognise the victory. This is clearly disrespectful towards voters," he said.