India has broadened its quest for long-term energy security with an agreement to explore and develop oil projects in Venezuela, the world's fifth-largest oil producer.

The agreement, signed by officials in the presence of Hugo Chávez, Venezuelan president, and Manmohan Singh, India's prime minister, offers state-owned Oil and Natural Gas Corporation a 49 per cent stake in the South American San Cristobal oilfield.

India's ONGC will join with Venezuelan national oil firm Petroleos de Venezuela in exploiting San Cristobal, which has the potential to produce 100,000 oil barrels per day. The venture follows several years of diplomatic talks between the two countries. Mr Chávez, on a four- day visit to India, said that Venezuela wanted to become a long-term supplier of crude oil to India, which imports more than 70 per cent of its oil needs, mostly from the volatile Gulf.

India's expanding economy, and its surging demand for energy, has fuelled a frenetic search to secure long-term energy supplies in new areas such as the Sudan, Russia, Burma, Australia and now South America.

Mani Shanker Aiyer, India's petroleum minister, has become one of the Congress-led government's most energetic members, and has launched several energy initiatives over the past few months.

As part of the latest agreement, he said India would offer Venezuela equity in an ONGC refinery in the south Indian town of Mangalore.

Venezuela's oil diplomacy with India represents an attempt to reduce its long term dependency on the US market, which imports 60 per cent of its crude oil. Relations between Venezuela and the US have deteriorated since the 1998 election of Mr Chávez, a leftwing-nationalist who is critical of US policies.