An exit poll and early returns suggest that Vladimir Putin has easily won a fourth term as Russia's president.

The nationwide exit poll showed Putin won 73.9% of Sunday's presidential vote.

ITV News Europe Editor Emma Murphy said Putin's team pointedly claimed the Skripal ex-spy poisoning crisis had boosted his victory.

The exit poll by the All-Russia Opinion Research Center reflect early results from Russia's Far East.

The Central Election Commission said with 21% all precincts counted, Putin was leading the race with 71.9% of the vote.

The exit poll showed Communist candidate Pavel Grudinin in second place with 11.2% of the vote, while ultra-nationalist Vladimir Zhirinovsky came in third with 6.7%.