Japanese automaker Nissan Motor has begun international arbitration against India to seek more than $770 million in a dispute over unpaid state incentives, according to a person familiar with the matter and documents reviewed by Reuters.

In a legal notice sent to Prime Minister Narendra Modi last year, Nissan sought payment of incentives due from the Tamil Nadu government as part of a 2008 agreement to set up a car manufacturing plant in the southern state.

According to the notice, Nissan said repeated requests to state officials for the payment, due in 2015, were overlooked and even a plea by the company’s chairman, Carlos Ghosn, to Modi in March of last year seeking federal assistance did not yield any results.

The notice, sent by Nissan’s lawyers in July 2016, was followed by more than a dozen meetings between federal and state officials and Nissan executives, said the person familiar with the matter, who did not want to be named.

The federal officials, from several ministries, assured Nissan the payment would be made, and it should not bring a legal case. But, in August, Nissan gave India an ultimatum to appoint an arbitrator, the person said, adding the first arbitration hearing will be in mid-December.

A Nissan spokesman said the company was “committed to working with the government of India towards a resolution,” but did not elaborate.

A senior Tamil Nadu state official said the government hoped to resolve the dispute without having to go to international arbitration. “There is no discrepancy with regard to the amount due, and we are trying hard to resolve the issue,” the official told Reuters.

Modi’s office did not respond to an e-mail seeking comment.

The case, brought against India for alleged violations of its Comprehensive Economic Partnership Agreement with Japan, is the latest in a string of international arbitration proceedings against the country by investors concerned about issues ranging from retrospective taxation to payments disputes.