Fresh doubt has been cast over whether next year's Grand Prix of America will go ahead as planned in New Jersey.
Formula 1 boss
Bernie Ecclestone told BBC Sport
the race would "definitely" not happen, before saying that it would if the track were ready in time.
Race president Tom Cotter insisted the track was ahead of schedule.
But on Saturday, when asked by the BBC News Channel's Inside F1 programme if New Jersey would happen, Ecclestone said: "No. Definitely, no."
It is the second time in two months the F1 chief has expressed reservations about the race.
"We'll have to see, I need to go and have another look," Ecclestone said. "What I've seen up to now, and what's been going on, I'm not quite as sure as they are.
"If they can get it completed and confirm to us it will be done, for sure, they'll be on the calendar."
Sebastian Vettel on the New Jersey track being ready
"If they can do that (the Freedom Tower) in one year, it shouldn't be a big problem to lay some Tarmac and put some fences up."
Previously, at the
Chinese Grand Prix in April, also in a BBC interview, Ecclestone said
: "Maybe the New York race will be 2013. It's if they're going to finish everything - it's a case of when."
The event, which runs along a street course overlooking the Hudson River and Manhattan skyline, is planned to be twinned with the Canadian Grand Prix next June.
Cotter said it would run the week after the Montreal race.
The New Jersey organisers held a promotional event last week at which world champion
Sebastian Vettel drove the track layout in a road car.
The Red Bull driver said: "The circuit is not anywhere near close to being ready, but as I said, it would be great.
"I think you can do a lot in one year. It was exactly one year since I last went to New York. They are building the Freedom Tower in Manhattan, and it's nearly done.
"If they can do that in one year, it shouldn't be a big problem to lay some Tarmac and put some fences up."
On the subject of a potential grand prix around the Olympic Stadium in London, Ecclestone said: "We're talking."
He added that it was "a couple of years away" before it could happen.
BBC F1 co-commentator David Coulthard was in New Jersey for the promotional event and drove the track.
He said: "They think they're ahead of schedule. They're talking about 12 months from now, but it's a lot of work - the road is so bowed in the middle. That's the main thing they have to do to have a proper street track."