Gazprom, Russia’s natural gas monopoly, signed a $4.2bn deal to acquire Italian oil group Eni’s 20 per cent stake in Gazprom Neft.

Alexei Miller, Gazprom’s chief executive, had long warned Eni that he would be exercising his right to buy the asset, but concerns over whether the Russian company would be able to come up with the financing created the possibility that the purchase would have to be delayed.