ONGC Videsh, the overseas arm of India's exploration major Oil and Natural Gas Corporation, has bagged a 15 percent stake in an oil block in the Nigeria-Sao Tome joint development zone.

"We have been informed of a 15 percent stake in one of the blocks in the Nigeria-Sao Tome joint development zone," Subir Raha, chairman and managing director of ONGC, told a press conference here Monday.

This marks ONGC Videsh's entry in Nigeria, the world's eighth largest oil producing country where India is seeking more equity stakes.

ONGC Videsh had bid for Block 2 in the Nigeria-Sao Tome joint development area as part of a consortium led by Devon/Pioneer/ERHC Energy.

The other partners in the block, besides ONGC Videsh with 15 percent stake, are Equator Exploration and A. & Harmattan with 10 percent stake each, and Foby Engineering and Momo Oil & Gas that hold the remaining stake equally.

In December, ONGC Videsh entered into a tie-up with Equator, the London Stock Exchange-listed oil and gas exploration company, to jointly bid for oil blocks in West Africa.

Though the two companies bid for two blocks, they did not win stakes in block four.

The governments of Nigeria and Sao Tome have fixed payment of $71 million as signature bonus for block 2, according to officials here.

With this new win, ONGC Videsh has acquired stakes in 15 exploration blocks overseas spread across over a dozen countries including Russia, Sudan, Vietnam, Iran and Myanmar.

As part of India's bid to secure energy security, ONGC Videsh is scouting for more opportunities at a time when competition has toughened with global crude prices scaling over $59 a barrel. The availability of good exploration blocks too is limited.