By Aditya Kalra and Abhirup Roy

NEW DELHI (Reuters) - Amazon.com Inc said talks have failed to resolve a bitter dispute over Future Retail stores and accused both it and Reliance Industries of fraud in Indian newspaper ads on Tuesday.

The U.S. e-commerce giant has been contesting a $3.4 billion sale of Future Group's retail assets to the Reliance conglomerate that was announced in 2020, and the case is currently before the Indian Supreme Court.

"I regret to say that we made efforts but I think nothing is possible by way of resolution," Amazon's lawyer Gopal Subramanium told the court. "The conversation is over."

Reliance, also India's biggest retailer, stunned Amazon when it began taking over prized real estate on Feb.25 with its staff suddenly showing up at many of Future's biggest stores to assume control, sources have told Reuters.

In earlier legal wrangling, Amazon had managed to block the sale of the retail assets.

But Reliance's sudden possession of more than 900 Future stores have landed what some analysts are calling a coup de grace that spoils Amazon's chances of untangling the transfer of Future's assets.

After the first seizures of stores, Amazon proposed talks separate from the Supreme Court hearing to resolve the issue but on Tuesday, lawyers for both Amazon and Future agreed those negotiations had collapsed.

Amazon had at the Supreme Court been seeking to return the legal dispute to arbitration in Singapore after Future had successfully obtained an Indian court order to stay those proceedings. On Tuesday, Future said it was not opposed to arbitration in Singapore.

Earlier in the day, Amazon had run large ads in leading Indian newspapers headlined "PUBLIC NOTICE" and saying that actions taken by Reliance and Future "have been done in a clandestine manner by playing a fraud on the constitutional courts in India."

Future lawyer Harish Salve told the Supreme Court on Tuesday that the company did not transfer the stores to Reliance voluntarily.

Future has said in filings this month that it could not pay rent at many outlets given its distressed financial situation and that Reliance, which had taken over many of its leases, had issued it with termination notices.

Reliance has not responded to a Reuters request for comment.

The newspaper ads were aimed at alerting all stakeholders, including Future's lenders, that the transfer of assets to Reliance is legally prohibited, according to a source with direct knowledge of the matter. The source was not authorised to speak to media and declined to be identified.