JERUSALEM — Prime Minister Benjamin Netanyahu on Sunday pledged "concrete solutions" to the cost of living in Israel but warned that reforms would be constrained by the fragility of the world economy.

A day after police said at least 50,000 people protested in Israel's "periphery" towns and cities, Netanyahu told his weekly cabinet meeting that he expects a committee to recommend reform options in September.

The committee, headed by respected economist Manuel Trajtenberg, was appointed last week after 250,000 people flooded into Israel's main cities to demand economic reforms to ease the cost of living and income disparity.

"I asked Professor Manuel Trajtenberg to submit... concrete solutions during the month of September, as quickly as possible -- but not too quickly," said Netanyahu, according to a statement issued by his office.

"We are dealing here with complex issues. We intend to arrive at concrete solutions, not generalisations, but rather concrete solutions to concrete problems of reducing the cost of living and the closing of gaps in the state of Israel."

But he warned that the committee would be required to take account of "various constraints," including the current fragility of the global economy.

"We must receive recommendations which characterise choice. A change of priorities means a choice, a choice between various constraints," the prime minister said.

Israel protesters, who have been taking to the streets in growing numbers since mid-July, are seeking broad reforms that will cut the cost of housing, health care, food and education.

They have urged the government to break up monopolies and rethink Israel's economic policy, which has gradually shifted from the socialist model that defined the early Jewish state towards the neo-liberal economic ideology espoused by Netanyahu.

The prime minister has reportedly said he is open to rethinking his economic policy, but he has also warned against spending outside the current budget and pledged to avoid cutting defence expenditure to pay for economic reforms.

Trajtenberg's committee is expected to present its recommendations to parliament's social and economic cabinet in about a month's time, but final legislative action is not expected until at least the end of October.

Israel's parliament, the Knesset, is in summer recess and though it will convene for a special session on Tuesday to discuss the social protests, it is not expected to vote on legislation until it resumes work fully on October 31.