Italian prime minister Silvio Berlusconi is due to attend a private birthday party for Russian prime minister Vladimir Putin on Wednesday on the shores of Lake Valdai, south of St Petersburg, with Russia’s controversial plans to build two more gas pipelines to Europe expected to be high on the agenda.

Franco Frattini, Italian foreign minister, confirmed on Monday that Mr Berlusconi was expected to fly to St Petersburg. He said he did not have a guest list or details of Mr Putin’s birthday celebrations.