Herbert Smith and Allen & Overy (A&O) have taken lead roles on a major Russian finance deal which has seen Gazprom Neft secure loans of up to $1.5bn (£963m).

The oil unit of Russia energy giant Gazprom has lined up financing of $1.35m (£866m) so far, a figure which could rise to $1.5bn if more lenders are signed up.

Herbert Smith is advising Gazprom Neft with a team led by Moscow-based energy finance partner Ed Baring.

A&O advised the lead arranging banks on the financing, including Bank of Tokyo-Mitsubishi UFJ, Natixis and Societe Generale, with the magic circle firm's team led by Moscow managing partner and project finance specialist Tony Humphrey,

The deal, which was announced earlier this month (3 August) has been structured as a pre-export finance facility which will mature in five years. Gazprom Neft said the money raised will be used for general corporate purposes and the refinancing of the company's existing debt.

The financing follows Gazprom's move to increase its ownership in Gazprom Neft last year with a $4.2bn (£2.7bn) deal which saw it add a further 20% stake previously owned by Italian utility company Eni. Cleary Gottlieb Steen & Hamilton advised Gazprom while Eni turned to Dewey & LeBoeuf.

Herbert Smith also won a major financing mandate for oil giant BP this month, advising the arranging banks of a loan of $3bn (£2bn) backed up by oil revenues in Angola, as part of a larger $5bn (£3bn) financing which also handed roles to Linklaters and Baker & McKenzie.