Israel is struggling to contain a huge and deadly forest fire that raged on for a fourth day, despite the efforts of firefighting planes from half a dozen countries.

The worst inferno in Israel's history has killed 41people, forced 17,000 to flee their homes and destroyed some 10,000 acres of woodland near the port of Haifa. By nightfall it had still not been brought under control.

Police spokesman Micky Rosenfeld said two people suspected of starting the blaze through negligence were arrested, after a commander said he believed it had spread from a camp fire that was not properly extinguished.

Israel Radio said the suspects were 16-year-old boys from a village bordering on the Carmel region woodlands where the fire was focused.

Foreign firefighting planes joined the battle to contain the blaze after Prime Minister Benjamin Netanyahu appealed for help because of a shortage of such aircraft in Israel.

Prime Minister Benjamin Netanyahu's government is facing public anger on Sunday over the huge fire.

Criticism also came from inside Netanyahu's fractious ruling coalition. "We need to take stock nationally as to how we as such an advanced sophisticated state achieved such a resounding failure," Welfare Minister Yitzhak Herzog of the centre-left Labour Party said on Israel's Army Radio.

Most critics have targeted Interior Minister Eli Yishai, whose job it is to oversee the firefighters. Many demanded that Yishai, of the ultra-Orthodox Shas party, a pivotal coalition partner in Netanyahu's government, resign for inadequate preparation of the firefighting system, which has not been able to bring the blaze under control.

"In a proper country, after such a failure you simply go home," said Yaron Dekel, host of a popular Israel Radio talk show, naming both Yishai and the Israeli fire chief.