London, May 24 (IANS): Model-turned-actress Megan Fox quit sci-fi movie "Transformers 3" after a blazing row with its director Michael Bay over her vanishing weight, it has emerged.

Fox's fragile frame concerned the director and his team on the set as they prepared to shoot the third instalment of the movie franchise that made her a star, reports thesun.co.uk.

Bay, 45, thought the 24-year-old looked "unhealthy" and wanted her to put on weight if she wanted to resume her role as Mikaela Banes in the third film.

This sparked off a massive fight and left the blockbuster looking for a new leading lady with production beginning this month.

"Megan stormed out after a huge row with Michael Bay. He thinks she has lost too much weight and looks too frail. He wanted her to put on some weight and it all kicked off," said a source from the film unit.

"The crew doesn't think she looks well, let alone the wholesome, curvy star they cast in the first film. She's going for this gaunt, pale image and it just looks unhealthy," the source added.