The Middle East Quartet appealed to Israel last night not to carry out its threat to cut off electricity to Gaza after a senior Palestinian official warned that it could destroy Tony Blair’s mission to rebuild the shattered Palestinian economy.

The Quartet - the United Nations, European Union, America and Russia – issued a communiqué after a meeting in New York calling “for the continued provision of essential services” to Gaza. The group also voiced “urgent concern” over the closure of important crossing points into Gaza, while strongly criticising the continued rocket fire from Gaza into Israel.

The Israeli Cabinet last week branded Gaza, which is run by the Islamist group Hamas, an “enemy entity”. The move cleared the way for Israel to turn off power to the area if Hamas does not crack down on antiIsraeli groups, such as Islamic Jihad, that fire the rockets.

In a confidential letter obtained by The Times, Saeb Erakat, the chief negotiator of the Palestinian Authority, cautioned of “grave” consequences if the cuts went ahead. “Such Israeli policies greatly undermine the success of the Quartet representative’s mandate to build the institutions and economy of a viable state in Gaza and the West Bank,” Mr Erakat told the Quartet.

Mr Blair has been given the task of helping the Palestinians to rebuild the infrastructure destroyed in their seven-year uprising against Israeli occupation. International aid groups have condemned Israel’s decision as “collective punishment”. But the threat does seem to have focused Hamas’s attention on the risk of total economic collapse as reports emerged that Hamas’s exiled leaders in Damascus were going to meet Islamic Jihad to discuss halting the rocket fire.

The Quartet was meeting yesterday to prepare for a US-sponsored gathering in Washington in mid-November to discuss ways out of the crisis between Israel and the Palestinians. A US official confirmed last night that Syria and Saudi Arabia – countries technically still at war with Israel – would be among 12 Arab states invited to attend the autumn conference.

The Israeli Government announced before last night’s meeting that it was ready to release another 90 Palestinian prisoners. Mr Blair was due to brief the Quartet last night as world leaders gathered in New York for a frenzy of diplomatic activity during the annual UN General Assembly session.

On the agenda

- UN Secretary-General will try to secure political commitment for negotiations on an international climate agreement today

- The Security Council is holding a summit on peace and security in Africa tomorrow

- British, French, German, Chinese, Russian and US foreign ministers will meet on Friday to discuss a possible tightening of sanctions on Iran