ONGC held a series of discussions with the state-run oil firm earlier this year over investing in the field’s development, after a 2004 deal with Sinopec looked to have dissolved.

However, the agreement on 10 December between Iran and the Chinese has placed ONGC in a difficult position, says an executive close to the talks.

He says the Indian firm had expected an initial contract to be signed as early as 2008. “ONGC were receiving all the right signals from Tehran about this and there was a fair amount of surprise that Sinopec talks were still ongoing through it all,” says the executive.

NIOC had promised the field to Sinopec under a 2004 agreement that required the Chinese company to develop the field and buy 10 million tonnes of liquefied natural gas a year over 25 years.