ST PETERSBURG, June 5 (Reuters) - Russia's Gazprom Neft

is talking exclusively with Hungary's MOL

about a potential sale of its stake in NIS, which

operates Serbia's only oil refinery, Gazprom Neft CEO Alexander

Dyukov said on Friday.

A recently formed Serbian company, Senator, said last month

it had offered 2 billion euros to Gazprom Neft and Gazprom for

their combined 56.2% stake in NIS.

NIS is subject to U.S. sanctions imposed in October over its

Russian ownership, part of broader measures targeting Moscow's

energy sector following its invasion of Ukraine. Washington has

pushed for the divestment of the Russian stake.

On Wednesday, MOL, Hungary's largest oil and gas company,

asked the U.S. government for a one-month extension to a June 6

deadline to complete talks to acquire the Russian stake in NIS.

Gazprom Neft owns 44.9%, Gazprom holds 11.3% and the Serbian

government has 29.9%, with the remainder held by small

shareholders and employees.