Tel Aviv, Dec 3 (DPA) A massive brushfire, the worst in Israel's history, raged unchecked for more than eight hours Thursday, burning thousands of acres of land, forcing villages to evacuate, and killing up to 40 people when their bus was engulfed in flames.

Prime Minister Benjamin Netanyahu described the blaze as "a catastrophe, the likes of which we have not yet known".

He appealed to Russia, Cyprus, Greece and Italy for help in putting out the fire, which began on the slopes of the Carmel hill, southeast of Israel's port city of Haifa, and rapidly spread.

Cyprus and Greece agreed to dispatch firefighting helicopters.

Some nine hours after the blaze was estimated to have begun exhausted firefighters, those from Haifa reinforced by teams from all over Israel, and by soldiers, were still struggling to bring it under control, but without success.

"We've lost control of the fire," a spokesman for Haifa's firefighting services was quoted as saying.

Public Security Minister Yitzhak Aharonovich said it was impossible to say when the fire could be brought under control. However, firefighters were speculated that as the fire spread west a major road linking Haifa with Tel Aviv to the south could act as a natural firebreak, or, failing that, the sea would.

At least 22 people were confirmed dead, but other accounts put the number as high as 40.

The fatalities were prison guards who had been drafted to help evacuate the 500 prisoners from a jail in the path of the flames. Their bus, with 50 people on board, was trapped by a falling tree and 40 of them burned to death. The others were injured.

The fire had been far from the road when the bus first set off, but spread about 1,500 metres in less than three minutes.

In addition to the prison, residents of the village of Beit Oren, about 10 km southeast of Haifa were ordered to hurriedly leave their homes as the fire approached. The blaze devoured homes and almost totally destroyed the village, reports from the scene said.

People living in the Druze village of Usafiya, about four kilometres east of Beit Oren were also ordered to leave their homes, and, after several hours residents of the villages of Ein Hod, Aiyn Chod and Nir Ezion, several kilometres to the south, were told to flee as well.

A local hotel also evacuated its guests, and the major road linking the area with the Tel Aviv region to the south was closed with police telling drivers to use the major coastal highway or other routes.

Hospitals in the region were placed on major alert.

It was unclear whether the fire was the result of an accident or whether it had been started deliberately as an act of arson.

Easterly winds helps the fire spread quickly and engulf dozens kilometres of forest, cutting off power to much of the area and sending up huge columns of smoke, which were visible on the coast, on the other side of the hill.

Huge flames also sent sparks upward into the evening sky, causing one witness to remark that the Carmel hill looked like "a volcano".

Another local resident said that while at first all she could see from her location by the sea was smoke, it later appeared as if the "entire Carmel hill was burning".