Rockhopper Exploration on Tuesday announced it has confirmed potential oil reserves of around 517m barrels off the Falkland Islands according to Bloomberg.
The British company said that an independent audit of the Sea Lion complex exceeded the amount in earlier estimates.
London-based Rockhopper would have a 258m barrel share of such a total.
Falklands offshore development has aggravated relations between Britain and Argentina, which maintains a sovereignty claim over the islands and their waters even though they are widely recognized as British Overseas Territory.
In 1982 the nations fought a brief war on and around the South Atlantic islands when Britain sent a vast naval task force to oust an occupying Argentine military presence.
In June 2015 an Argentine judge ordered the seizure of $156m of assets belonging to Rockhopper and other foreign firms but the ruling is seen as being largely symbolic and unenforceable.