An estimated 13,000 people were forced to flee their homes in northern Israel on Thursday and early Friday, as the worst bushfire in Israel's history raged unchecked for 14 hours, killing 40 people and devouring everything in its path.

The fire broke out shortly before noon Thursday on the Carmel hill, southeast of the port city of Haifa, and Prime Minister Benjamin Netanyahu described it as “a catastrophe, the likes of which we have not yet known”.

He appealed to Russia, Cyprus, Greece, Italy and other countries for help in putting out the fire and by early Friday morning, some 24 firefighting aircraft, as well as other equipment, from countries including Greece, Cyprus, France and Egypt, were mobilising for Israel or were already on their way.

The aircraft were set to go into action at first light, around 04:00 GMT. The fire swept unchecked for hours, and after about 14 hours exhausted firefighters, those from Haifa reinforced by teams from across Israel, and by soldiers, were still struggling without success to bring it under control.

Army bulldozers were clearing paths through the Carmel forest to provide access for fire trucks. “We’ve lost control of the fire,” a spokesman for Haifa's firefighting services was quoted as saying early Thursday evening.

Public Security Minister Yitzhak Aharonovich said it was impossible to say when the fire could be contained. At least 40 people were confirmed dead, their charred bodies identified as the evening wore on.

They had been prison guards who had been drafted to help evacuate 500 prisoners from a jail in the path of the flames. Reports said their bus either was trapped by a falling tree, or the driver lost control of the vehicle, and they burned to death.

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

In addition to the prison, residents of the villages in the vicinity of the fire were ordered to leave their homes. One village, Beit Oren, the first to be evacuated, was almost totally destroyed by the fire, reports from the scene said.

At around 1 am on Friday (2300 GMT on Thursday) Haifa Mayor Yona Yahav gave the order to evacuate some streets of a suburb on the city's outlying districts, close to the area of the blaze.

He said there was no immediate danger of the fire reaching the suburb, but added that "we're not taking any chances".

Netanyahu had said earlier in the evening that more evacuations would be ordered as necessary.

Hospitals in the region were placed on major alert. Hopes that a major road linking Haifa with Tel Aviv in the south would act as a fire-break appeared to be unfounded.

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, and the dry ground caused by a severe drought, helped 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 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.”