The race, at Spa-Francorchamps, was in doubt after its promoter filed for bankruptcy last October but negotiations took place between the local council and Formula One chief Bernie Ecclestone.

The Englishman claimed he was prepared to act as promoter but further doubts over the race emerged last month.

Ecclestone demanded redevelopment of the historic circuit, but with so little time before the September race, that would have meant the cancellation of other races.

The FIA confirmed in a statement that the Belgian authorities had requested the cancellation of this year's race.

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

"The FIA hopes that the event will be included once again in the Formula One world championship calendar from 2007 onwards."

The announcement is the latest crisis to hit Formula One's most popular circuit, which was thrown off the 2003 schedule in a row over tobacco advertising.

Facilities at Spa are in need of modernisation, with the current pits and paddock complex unable to cope with the demands of an 11th team after Super Aguri's entry was accepted.

That work will be done but the circuit, which is owned by local authorities, were reluctant to carry it out in time for this year's race.

That would have meant postponing the profitable 24-hour race as well as the visit of Germany's prestigious DTM series in favour of holding on to the loss-making grand prix.

Wednesday's news trims the 2006 Formula One calendar down to 18 races. The Belgian Grand Prix was scheduled for September 17, one week after the Italian race.

But there will now be a three-week autumn break after the Monza race before the Chinese Grand prix on October 1 in Shanghai.

The announcement is the latest crisis to hit Formula One's most popular circuit, which was thrown off the 2003 schedule in a row over tobacco advertising.

Facilities at Spa are in need of modernisation, with the current pits and paddock complex unable to cope with the demands of an 11th team after Super Aguri's entry was accepted.

That work will be done but the circuit, which is owned by local authorities, were reluctant to carry it out in time for this year's race.

That would have meant postponing the profitable 24-hour race as well as the visit of Germany's prestigious DTM series in favour of holding on to the loss-making grand prix.

Today's news trims the 2006 Formula One calendar down to 18 races. The Belgian Grand Prix was scheduled for September 17, one week after the Italian race.

But there will now be a three-week autumn break after the Monza race before the Chinese Grand prix on October 1 in Shanghai.