Cairn Energy has threatened to seize Indian government assets following a $1.2bn (£880m) award from a long-running corporate tax case.
The UK-based energy firm was awarded damages by an international tribunal in the high-profile dispute with the Indian government last month.
Cairn has started identifying assets it could seize if the Indian government doesn’t comply with the order.
Sources have said that these could include planes and ships.
The case was filed after income tax officials seized Cairn’s 10% stake in its Indian subsidiary.
In December the tribunal ruled unanimously that Delhi had violated the 2014 UK-India bilateral investment treaty.
It ordered Delhi to pay $1.2bn in damages, plus interest and costs, to compensate Cairn for the shares as well as confiscated dividends.
But since the 582-page judgment was issued, Indian prime minister Narendra Modi’s government has given no indication about whether it intends to honour the verdict, even though payment was due immediately.
Cairn has sent a letter to Indian government officials, seen by both Reuters and the Financial Times, saying its shareholders “expect early resolution, failing which they will expect Cairn to pursue the award in conformity with its rights under the treaty”.
“The award can be enforced against Indian assets in numerous jurisdictions around the world for which the necessary preparations have been put in place,” the letter added.
Although the letter did not specify when assets might be seized, possible targets could include those owned by public sector enterprises such as state-owned Air India.