Bernie Ecclestone has added fuel to the speculation that he won't renew the deal with the Indianapolis Motor Speedway after hitting out at the organisers of the United States Grand Prix, claiming they are not doing enough to promote Formula 1.

The US Grand Prix has been on temporary watch since 2005 and the 'Michelin-gate' farce, although even before then Ecclestone has complained that Formula 1 is not receiving sufficient attention when compared to the Indy 500 or NASCAR.

Indeed, having hinted in the media earlier in the week that Formula 1 does not need the American market to progress, Ecclestone's comments to Reuters suggest this weekend's race could be the last at Indianapolis at least.

"They haven't done anything to really get behind it have they?," he said. "We arrive in town, what do we get? We get banners saying the Indy 500. Not really the way to promote Formula One. They haven't got behind it, full stop."

Other American venues have been mooted in the past, namely a return to Las Vegas, but it is possible United States could be forced off the calendar in light of new venues in Valencia and Singapore next year, as well as Abu Dhabi, India and South Korea in the future.

Although a deal is thought to be on the table, Ecclestone has yet to put pen to paper but admitted he is in talks with IMS owner Tony George about extending the contract.

"We're talking to everybody. We were speaking with (IMS owner) Tony (George) yesterday, we'll chat to him next week and see what we come up with."