Gazprom's deputy chief executive Alexander Medvedev said today that the company has sent letters to the five international oil companies to open talks over development help for the huge Arctic field, which has enough gas to supply the US for more than five years.

"We will start these discussions in February," Medvedev was quoted by Bloomberg as saying.

Chevron, ConocoPhillips, Norsk Hydro, Statoil and Total had bid to help develop Shtokman's 3.7