Monsoon Wedding director Mira Nair's upcoming production of Vanity Fair faces uncertainty after it emerged that US star Reese Witherspoon may have to delay shooting.

Producer Janette Day said that the adaptation of William Makepeace Thackeray's novel might only be delayed for a few weeks if a compromise can be reached, but that the project could be pushed back to August. Nair was to start shooting in the UK during the first quarter this year.

"This only happened this week," said Day, who hopes to firm up a new start date within days.

Marking Nair's follow up to 2001 hit Monsoon Wedding, the Napoleonic Wars-set story of how Becky Sharp climbs the London social ladder is being financed by Focus Features, the Vivendi Universal speciality arm.

Day and former Granada Film chief Pippa Cross worked on Vanity Fair at Granada, continuing with the highly-anticipated project independently when the commercial broadcaster closed down its feature production operation in September. The broadcaster said at the time it would honour its commitment to Vanity Fair, along with Craig Ferguson's romantic comedy All American Man.

Vanity Fair's wobble comes as the UK production sector seemed to have shaken off last year's spate of collapses, which saw high-profile shoots such as To Kill A King, Borgia and Edgardo Mortara flounder. Mercifully few projects have collapsed recently, even if this week's figures from Government-backed support body the Film Council showed that the number of films was down from 51 in 2001 to 42 last year.