Around 50 police, rescue workers and doctors mobilised in southern France on Tuesday to remove an obese man who was no longer able to raise himself from the floor of his bedroom, and too big to be carried out through the door or down the stairs.

Alain Panabiere, 53, had been stranded for months at his home in central Perpignan "in all likelihood after breaking his leg," his lawyer Jean Codognes said.

He had been fed by his brother but his condition deteriorated rapidly, and in late October the lawyer wrote to French Interior Minister Gerald Darmanin pleading for an emergency rescue.

A few days later, Panabiere, who weighs some 300 kilogrammes (660 pounds), and France's Anti-Obesity League also filed a legal complaint alleging "failure to assist a person in danger."

"This is a high-risk operation," Codognes said, as police cordoned off the narrow street as the rescue got underway at Panabiere's two-storey home.

Police said neighbours were also asked to leave their homes in case of accident.

Having reinforced the building's structural stability, workers cut open a passage through an exterior wall on the upper floor, according to AFP journalists at the scene.

Panabiere was then fitted with an IV drip and carefully carried to a metal storage box suspended from a crane outside, so he could be lowered while lying down to a waiting ambulance.

"When you get a person moving again after they've been immobilised for two to five years, there's a risk of cardiac decompensation and vein thrombosis," said Antoine Avignon, head of endocrinology, diabetes and nutrition and the nearby hospital in Montpellier.

"You're reviving a cardio-vascular system that has been at rest for a long time," he said.

Panabiere will be treated in the city of Montpellier before being transferred to a rehabilitation centre in a few weeks, Avignon said.