THE growing diplomatic scandal over the poisoning of an ex-spy in Britain will not disrupt Russia’s presidential campaign, Vladimir Putin’s spokesman has said.

Dmitry Peskov told reporters the nerve agent attack on Sergei Skripal “doesn’t affect” the campaign for Sunday’s election, which he called Russia’s top priority.

He strongly denied Russian responsibility in the March 4 attack.

The Russian campaign remains lacklustre just three days before the vote, and Putin is the overwhelming favourite to win another six-year term after 18 years in power, riding in part on his argument that he must stand up to Western aggressors.

Opposition candidate and former TV star Ksenia Sobchak is holding a big rally on Thursday, after breaking down in tears at the final televised debate on Wednesday night. She was the only candidate to criticise Putin.

Putin’s self-assurance and relaxed demeanour reflects the stress-free campaign the 65-year-old has run, in stark contrast to the tension ahead of the 2012 election amid massive protests against his rule.

His popularity soared after Russia annexed Ukraine’s Crimean Peninsula in 2014, and his ratings still top 80 per cent.

Despite a weak economy and spiralling tensions with the West, he is on track to become the nation’s longest-serving ruler since Stalin.