PARIS, July 22 (Reuters) - French police said at least 24 people died on Sunday when a coach carrying Polish pilgrims plunged down a hillside and burst into flames near the southeastern French city of Grenoble.

The coach, carrying around 50 Polish nationals, apparently suffered problems with its braking system while descending a steep incline. It left the road, cleared roadside barriers and careered downhill, emergency officials said.

The vehicle came to rest on the banks of the river Romanche and burst into flames, they added.

"The toll has now risen to 24 dead, 24 injured and two missing," gendarme (police) Lt-Colonel Thierry Rousseau told Reuters by telephone. Of the injured, 12 were in a serious condition, he added.

Local officials said the coach's speed and the state of its brakes may have been factors in the accident.

Pictures broadcast on LCI television showed rescue workers treating survivors on the grassy banks of the Romanche, the carcass of the coach still smouldering in the background.

Debris was strewn around the river bank where the coach finally came to rest.

French Prime Minister Francois Fillon would visit the crash site later in the day, his office said. The Polish consul in Lyon was also heading there, Warsaw said.

Local media reported between four and nine people were in a serious condition after the smash, which happened at the Laffrey gradient, a notorious accident blackspot.

In July 1973, a Belgian coach crashed near the same spot, killing 43 people.

Polish television said the Polish pilgrims were from parishes in the Szczecin area of northwestern Poland, who were due to return home on Tuesday. The Polish Foreign Ministry has set up telephone hotlines for relatives.

The Poles had been attending a pilgrimage at the nearby Notre-Dame de la Salette sanctuary along with nationals from Belarus, Ukraine, France, Russia and Britain.

Separately, the PAP news agency in Warsaw reported that a 71-year-old Israeli citizen was killed in a coach crash in southern Poland on Sunday.

PAP said five other people including the dead man's son had been injured in the crash, which happened when one lorry rammed into another which had parked behind the stationary coach.

Most of the coach's passengers were Ukrainians and Poles returning from jobs in Germany and German tourists travelling to the Crimea.

(Additional reporting by Guy Kerivel and Rob Strybel)