MOSCOW • Russia is set to re-elect Mr Vladimir Putin to a historic fourth Kremlin term today, as the country faces increasing isolation over a spy poisoning in Britain and a fresh round of US sanctions.

Mr Putin, who has ruled Russia for almost two decades, is polling at around 70 per cent and is sure to extend his term to 2024 despite a lacklustre campaign.

In the run-up to the election, he and a compliant state media have sought to reinforce his image as the man who restored stability and national pride after the humiliating collapse of the Soviet Union.

Mr Putin has also sought to emphasise Russia's role as a major world power, recently boasting of its ''invincible'' new weapons and doubling down on Moscow's support for the Syrian regime in a bloody civil war.

Rising tensions with the West over the poisoning of former double agent Sergei Skripal in Britain, and new sanctions from Washington over alleged election meddling, strengthen the impression of a Russia at loggerheads with the rest of the world. Mr Putin, who has run under the slogan ''A strong president - a strong Russia'', has declined to take part in televised debates and shot no new material for his own campaign advertisements.

He is up against seven other candidates, including millionaire communist Pavel Grudinin and ex-reality TV host Ksenia Sobchak, but none are polling more than 8 per cent.

The authorities are seeking a high turnout to add greater legitimacy to a new term for Mr Putin, who is already Russia's second-longest serving leader since Joseph Stalin.

Polls opened in Russia's far east yesterday and close in Kaliningrad today. Overall turnout is expected to be between 63 and 67 per cent, according to official pollsters.

AGENCE FRANCE-PRESSE