State-owned firms Oil & Natural Gas Corporation (ONGC) and Oil India Limited (OIL) have signed a deal with Videocon Industries to buy its 10 per cent stake in a Mozambique gas field for around $2.5 billion.

The acquisition, which will be done through a special purpose vehicle jointly owned by ONGC Videsh (OVL) and OIL, is expected to provide India with an estimated 6 million tonnes of liquefied natural gas (LNG) per year.

OVL, the overseas division of ONGC, said the deal marked its entry into a world-class gas project that would help it achieve its targets of 20 and million tonnes of oil equivalent by 2018 and 2030, respectively.

Sudhir Vasudeva, chairman of OVL, said, "Considering the growing importance of natural gas in the primary energy basket, this acquisition is a significant step by OVL/ONGC group towards the energy security of our country."

The deal with Videocon is ONGC's third major international acquisition since it acquired Hess Corporation's 2.7 per cent stake in Azerbaijan's biggest oil field for $1 billion. In November last year, it signed a deal with ConocoPhillips to purchase its 8.4 per cent stake in Kazakhstan-based Kashagan project for $5 billion.

OIL officials said that gas production from the Rovuma gas field should start by 2018 with an initial annual production of 10 million tones, which will jump to nearly 30 million tones per annum by 2024

In the after-hours trading, ONGC shares gained 4.5 per cent, while OIL shares slipped 0.79 per cent.