New Delhi: Abu Dhabi National Oil Company (Adnoc) on Monday joined Saudi Aramco to pick up stakes in a $44-billion refinery at Ratnagiri, Maharashtra, and a petro-chemical project even as they are looking at other investment options in the country, including retailing fuel and acquiring stakes in crude storage facilities.

Saudi Aramco, the world's largest oil producer, also said it had sufficient reserves to offer crude in emergency, allaying fears that the US sanction on Iran and the economic crisis in Venezuela could hit supplies.

Aramco and Adnoc will together hold 50 per cent in the 60-million-tonne-a-year refinery and the adjacent 18 million-tonne-petrochemical complex; the remaining stakes will be split among state-owned Indian Oil (IOC), Bharat Petroleum (BPCL) and Hindustan Petroleum (HPCL).

Saudi Aramco CEO and president Amin H. Nasser said for both Saudi Arabia and UAE "strategic business investment with the world's fastest growing oil consumer has reached an irresistible tipping point".

The MoU was signed between Nasser and Ahmed al Jaber, UAE minister of state & Adnoc group chief executive officer.

On the amount of stake Adnoc and Aramco would hold, Nasser said, "between us it is 50 per cent and terms of how much percentage for each is being discussed between the two partners".

Aramco will supply half of the crude oil required for processing at the refinery that will be commissioned by 2025. Adnoc will also supply some crude. "With oil demand almost doubling to 10 million barrels per day by 2040, India's access to adequate, affordable oil has never been more important," Nasser said.

Aramco had signed an agreement in April with Ratnagiri Refinery & Petrochemicals - a joint venture among IOC, BPCL and HPCL - under which it had made its commitment to supply crude and had said it would bring a partner at a later date.

Aramco said it was looking at not just refining oil but also sell downstream products in the market.