Shops in occupied East Jerusalem have downed their shutters in solidarity with hunger-striking Palestinian prisoners in Israeli jails, many of whom have been in hospital.

Business owners closed their shops on Thursday in the normally bustling Old City in Israeli-annexed East Jerusalem, an AFP news agency correspondent said, to observe a strike called by an umbrella group of various political parties and factions.

The Palestinian National and Islamic Forces said there would be a demonstration in the evening outside the offices of the Red Cross, also in East Jerusalem.

On Wednesday, the Palestinian leadership called for international intervention over the hunger strike, asking that Israel be held responsible for the health of the prisoners.

A letter addressed to the UN Security Council and the European Union, signed by senior Palestinian figure Saeb Erakat, said more than 400 prisoners had joined the strike, of whom approximately 130 had been refusing food for more than six weeks.

"We call on you to call on Israel to annul the policy of administrative detention and to condition deepening your bilateral ties with Israel pending Israel's fulfilment of all its obligations," he wrote in English.

Force-feeding inmates

Most of the strikers are administrative detainees who are being held without charge for indefinitely renewable six-month periods in a procedure dating back to the British Mandate (1920-1948).

Sivan Weizman, a spokeswoman for the Israel prisons service, told AFP on Thursday that the current hunger strike was the longest staged by Palestinian detainees so far.

In contrast to Erakat's claim, she said 250 inmates were refusing food, of whom 80 were being treated in hospital.

Earlier this week, the Israeli parliament approved the first reading of a bill to enable doctors to force feed hunger strikers.

It must pass two more readings before becoming law.

Some 5,000 Palestinians are being held in Israeli jails, with nearly 200 in administrative detention.