A British millionaire is being hunted by cops after his girlfriend was found battered to death in a Paris hotel room.

The 40-year-old man, who has not been named, is believed to be heading towards the French Riviera in his Porsche 911 sports car.

French police said they wanted to speak to him "urgently" after the naked corpse of his 36-year-old lover was found covered in wounds in a bath at the $2,390-a-night Hotel Bristol.

Cops said the victim, who is believed to be a Polish businesswoman, had checked into the four-star hotel alone on Monday before her boyfriend checked in early on Tuesday.

The woman's bruised body was discovered by a cleaner that evening.

Officers said she had been beaten repeatedly with a blunt object and that a fight had clearly taken place in the trashed room.

The English boyfriend had fled and was believed to be on the run, police said.