ONGC Mittal Energy Ltd (OMEL) and its consortium partners, Germany's Wintershall and Denmark's Maersk Oil, have surrendered the Turkmenistan offshore exploration block in the Caspian Sea.

OMEL, a joint venture between ONGC Videsh Ltd and LN Mittal's Mittal Investment Sarl, had completed formalities for surrendering the two blocks

OMEL had invested about $28 million to acquire a 30-per cent stake in the offshore exploration block 11-12 in Turkmenistan, reports quoting sources said, adding that the decision to abandon the field was taken after initial prospecting turned out to be not very attractive.

Wintershall had 34 per cent stake in the Turkmenistan block and Maersk Oil had 36 per cent participating interest in the block.

OMEL also recently opted out of a gas block in Trinidad and Tobago. The Turkmenistan block is the fourth oil block acquired by OMEL overseas.

OMEL has three active blocks - one in Syria, which is a producing asset and two highly prospective blocks in Nigerian deepwater - OPL 279 and OPL 285.

OMEL is reported to have started its first phase of exploration in the Nigerian block OPL-279.

The union cabinet has, meanwhile, sanctioned $359 million to ONGC Videsh Ltd, the overseas arm of state-run ONGC Ltd, for the execution of the first exploration phase in two Nigerian deepwater blocks.

The cabinet committee on economic affairs (CCEA) has authorised OVL to provide funding support to OMEL for OVL's share of expenditure of $195 million for the OPL 279 block and $164 million for the OPL 285 block in Nigeria as per work programme and budgeted estimates for the first exploration phase, inclusive of signature bonus and acquisition cost, according to a government release.

Petroleum minister Murli Deora is expected to visit Nigeria later this month.