The Belgian Grand prix has been cancelled this year to allow the Spa track to be improved, Formula One's ruling body said on Wednesday.

The race was scheduled for September 17 but has been in doubt for several weeks because of problems over who would promote it after the previous promoter went bankrupt due to poor ticket sales.

"The Belgian National Sporting Authority, the RACB, has written to notify the FIA of the withdrawal of the 2006 Belgian Grand Prix from the FIA Formula One World Championship," the FIA, the sport's ruling body, said in a statement.

"The withdrawal has been made in order to allow the completion of extensive improvement work to facilities at the Spa-Francorchamps circuit."

The FIA said it hoped the Grand Prix would be raced from 2007 onwards.

Formula One supremo Bernie Ecclestone had been in negotiations with the regional government of southern Wallonia about the race's future.

A spokesman for the Walloon government said they had been informed of the decision by the FIA and will be releasing a formal statement on Wednesday.

"The news was expected, but it will give us time to organise something even better in 2007," the spokesman said.

"We are continuing to analyse the situation."

• Formula One coverage