French film legend-turned-activist Brigitte Bardot took a swipe at Sarah Palin on Tuesday, saying the US vice presidential candidate was a disgrace to women.

"I hope you lose these elections because that would be a victory for the world," Bardot wrote in an open letter to Republican John McCain's running mate in the November vote.

"By denying the responsibility of man in global warming, by advocating gun rights and making statements that are disconcertingly stupid, you are a disgrace to women and you alone represent a terrible threat, a true environmental catastrophe," wrote Bardot.

The screen icon from the 1960s, who now heads an animal rights foundation, went on to assail Palin for supporting Arctic oil exploration that could jeopardise delicate animal habitats and for dismissing measures to protect polar bears.

"This shows your total lack of responsibility, your inability to protect or simply respect animal life," Bardot wrote.

In a final salvo against Palin, the 74-year-old star picked up on Painless depiction of herself as a pitbull wearing lipstick and said she "implored" her not to compare herself to dogs.

"I know them well and I can assure you that no pitbull, no dog, nor any other animal for that matter is as dangerous as you are," Bardot wrote.