Formula 1 boss Bernie Ecclestone has cast doubt on whether the new Grand Prix of America in New Jersey will take place in 2013 as planned.

The event on public roads alongside the Hudson River overlooking New York City had been expected to join the calendar in June next year.

But Ecclestone told BBC Sport there was some doubt about whether the track would be ready in time.

"Maybe the New York race will be 2013," he said. "It's a when - 2013 or 2014."

It is the first time any doubts have been expressed about the much-anticipated event, which is the second new Formula 1 race scheduled to take place in the USA in the next 14 months.

The first is the United States Grand Prix, which is scheduled to take place on a new track being built in Austin, Texas, as the penultimate race of this season on 18 November.

Texan circuit bosses insist the race will go ahead, but there have been continuing reports in the US of legal problems and doubts that the track will be ready in time.

The Texas race has had a troubled development. The initial promoter fell out with the track's bosses and had his contract ripped up by Ecclestone.

The race was only included on this year's calendar after the new promoter agreed to pay the sanctioning fee at the 11th hour before Ecclestone submitted a final calendar to governing body the FIA in December last year.

Recently, there have been reports in the US of delays in building the track as well as ongoing issues surrounding the management of the track and event.

Bosses have continued to insist that the race will take place as planned.

Ecclestone also said that a proposed deal that would see the French Grand Prix return to the calendar and alternate year-to-year with the Belgian event at Spa-Francorchamps was a real possibility.

The arrangement is expected to start in 2013, with the French race at the Paul Ricard track near Marseille rather than at Magny-Cours near Nevers, which last hosted the race in 2008.

Ecclestone said: "We don't want any more races. They're quite close and they're French-speaking. Spa have agreed; apparently they're going to do it in Ricard."

Ecclestone is the former promoter of the Belgian Grand Prix and his family trust owns the Paul Ricard track, which has been used for occasional F1 testing in recent years.

The French event remains in some doubt, however.

It depends on raising the required funding and although the current government, which is facing an imminent general election, has made it clear it supports the race, it has said it will not provide any state funding.

And if President Nicolas Sarkozy's party loses the election, it is not clear whether the new government would back the race, and if they did whether they would be happy for it to take place at Paul Ricard rather than Magny-Cours, which has long links with their party.