Indianapolis Motor Speedway chiefs have again said that the door remains open for Formula One to return to the venue, despite the fact that the United States Grand Prix is missing from the provisional schedule for the 2009 season.

Indy hosted the US Grand Prix from 2000 to 2007 but was missing from the calendar this season after failing to reach an agreement with F1 boss Bernie Ecclestone to return for an eighth straight year.

Well aware of the need to make the event financially viable, the circuit was looking to try and secure the backing needed to make a return in 2009 but Ecclestone appeared to pour cold water on a race earlier this month when he said that a US race wasn't something he considered as 'fundamental'.

The provisional calendar for 2009 released by the FIA duly didn't contain a return to Indianapolis, with the only addition to the circuits visited in 2008 being the first ever race in Abu Dhabi.

Despite that, Indianapolis Speedway president Joie Chitwood told the Indy Star that he felt there was still a home for F1 in the United States and that the race could still take place next year, although it gets 'tougher and tougher' every day to bring the event back.

"I still think there's a home for F1 in the U.S, but it's getting the right partner to activate and promote it," he said. "That's a vital component.

"The door remains open for the future. There continues to be dialogue."

"We want to stress it's just a provisional schedule," added Speedway spokesman Ron Green, speaking to The Associated Press about the omission of the US Grand Prix from the 2009 F1 calendar. "We continue to be interested in the return of the United States Grand Prix.

"Discussions will continue. We believe a return of Formula 1 to our calendar, especially during our centennial era, the period between 2009-2011, would be appropriate – but it must be on terms reasonable to all the groups."