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Construction of the 2012 United States Grand Prix track has been halted after the circuit's owners said they have not yet been granted a contract to stage the race.

Circuit of The Americas officials in Austin, Texas, said workers had been told to down tools while they await confirmation from Formula 1 officials.

"The failure to deliver race contracts gives us great concern," they said.

On Saturday, F1 boss Bernie Ecclestone cast doubt on the Texas race.

"Local businesses, fans and the State of Texas are counting on us," added Red McCombs, a founding group partner.

In a separate announcement, it was confirmed that public funds would not be used to pay for the development of the track.

"Let me state clearly: We have not paid out any money for the Formula 1 event," said Susan Combs from Texas Public Accounts.

"The only dollars that can be spent on the United States Grand Prix are tax revenues attributable to the successful running of a race. The state of Texas will not be paying any funds in advance of the event."

The United States last hosted a grand prix at Indianapolis in 2007, but Ecclestone has long been seeking a new venue to bring the sport back to one of its biggest markets.

In 2010, Ecclestone announced that a purpose-built circuit would be constructed near Austin and would host the US Grand Prix until 2021.

But last week US Grand Prix circuit chiefs were left bemused when he cast doubt on next year's race, describing negotiations as "an uphill struggle".

"Austin? I wouldn't want to put my money down that that will happen," he said. "I hope it will and we are doing our best to make it happen, but I wouldn't want to say 'yes'."

In addition, it was announced in October that a for 10 years from 2013.

Steve Sexton, president of the Austin circuit, said in response to Ecclestone's comments: "Our funding is secured and construction is on schedule, so we don't understand these comments.

"He [Ecclestone] has expressed great interest in the Austin race and in expanding the F1 brand into the US."

The dispute comes after next season after .