LONDON • The US Grand Prix in Austin remained in doubt on Wednesday after the official 2016 Formula One calendar was published with an asterisk against the Texas race due to doubts about funding issues.

The International Automobile Federation (FIA) said it had approved a schedule with a record 21 races and just one change with the new version pairing Mexico with Texas instead of Brazil.

The race in Austin, scheduled for Oct 23, is subject to an agreement with the promoter and national sporting authority.

Mexico was brought forward from Nov 6 to Oct 30. That change had been sought by Mexican organisers, whose grand prix returned to the calendar this season after a 23-year absence and drew a crowd of 135,000 on race days.

The earlier date means it will again be just before the national Day of the Dead holidays.

This year's US Grand Prix at Austin's Circuit of the Americas was hit by torrential rain.

It suffered a further financial setback when news emerged of a reduction in the subsidy paid by Texas state authorities.

Formula One supremo Bernie Ecclestone expressed concern for the future of the race last month after reports said the subsidies were being reduced by more than 20 per cent to around US$19.5 million (S$27.5 million).

"If it's changed, it's going to be difficult to continue the race in Austin," he had told the Austin American-Statesman.

"To use a technical term, I think we're screwed," Circuit of the Americas chairman Bobby Epstein, who has to pay Ecclestone a significant annual sum in race hosting fees, had told the same newspaper.

"The big question now is: Is the race coming back?"

The Austin circuit is Formula One's first purpose-built track in the United States and has hosted a grand prix since 2012.

Mercedes driver Lewis Hamilton has won there three times, including this year to clinch his third world title.

REUTERS