Russia largest oil producer OAO Rosneft's (ROSN.RS) First Vice President Pavel Fedorov moved to work as a deputy energy minister Thursday, marking the first government appointment since Vladimir Putin returned as President at March 4 elections.

Analysts and investors are watching closely for any hints to who will join the new cabinet, which is expected to take shape only late May.

The Kremlin said Thursday that all changes to the cabinet will be announced after the parliament approves the new Prime Minister in May. Prior to elections Putin promised that current president Dmitry Medvedev will head the government.

Fedorov worked at Rosneft since April 2010. He will be responsible for the development of the oil industry, investment and tax policy.