NEW DELHI (Reuters) – India has challenged in Singapore an international arbitration court’s verdict against it over a $2 billion tax claim involving Vodafone Group Plc, a senior government official told Reuters on Thursday on condition of anonymity.

Vodafone in September had won the case against India, ending one of the most high-profile disputes in the country that had caused concern among investors over retrospective tax claims on companies.

An international arbitration tribunal in The Hague had ruled that India’s imposition of a tax liability on Vodafone was in a breach of an investment treaty agreement between India and the Netherlands. India had 90 days to appeal the ruling.

India’s finance ministry did not immediately reply to an email and message seeking comment on the story.

India lost another international arbitration case this week, against Cairn Energy, over a tax dispute. It has been ordered to pay the UK-listed company over $1.2 billion in damages and costs.

India is expected to challenge this ruling too given the size of the award, said the senior government official, who did not want to be named as the decision was not public yet.

India has faced a string of arbitrations by investors including Deutsche Telekom, Nissan Motor Co, Vodafone and Cairn Energy over issues ranging from retrospective taxation to payment disputes.