Israel resumed fuel supplies to the Gaza Strip's main power plant on Tuesday, offering limited respite from a blockade that plunged much of the Hamas-ruled territory into darkness and touched off international protests.

The shipment included at least three days' worth of European Union-funded fuel for the generating plant, which shut down on Sunday after Israel sealed border crossings in what it termed a response to Palestinian cross-border rocket salvoes.

"We can restart production 12 hours after the fuel arrives," Derar Abu Sissi, the plant's general director, told Reuters.

Israel said it would also allow in 500,000 litres (132,000 U.S. gallons) of diesel for generators, a supply of cooking gas and 50 trucks of food and medicine, though restrictions on petrol for cars remained.

"Our approach now is to assess what is acutely lacking, and permit imports on that basis," Israeli Defence Ministry spokesman Shlomo Dror said.

The European Union and international agencies denounced the Israeli closure as illegal "collective punishment" against Gaza's 1.5 million residents, many of whom depend on foreign aid. Gazans stockpiled food and medical officials.

Israel denied there was a humanitarian crisis in Gaza and said its measures were a justified reaction to rocket and mortar attacks, some of which were carried out by Hamas.

The decision to allow in emergency supplies, Israeli officials said, followed a decline in the number of salvoes.

"We have learned that Hamas controls the rocket fire. It has to be clear to the residents of the strip that it is Hamas's conduct that harms them, not Israel's," Dror said.

ROCKETS

Hamas refuses to give up its fight against the Jewish state and opposes peace moves by Palestinian President Mahmoud Abbas, whose administration condemned the Israeli closure as harmful to diplomacy.

Palestinians launched at least one rocket into Israel from Gaza on Tuesday, causing no damage, the military said. There was no immediate claim of responsibility.

The Gaza power plant ordinarily provides only 30 percent of the territory's electricity, but its closure affected a far greater proportion of the population because of the way the power grid system works.

An EU official said Israel gave the European Union open-ended approval to resume normal fuel supplies for the plant.

"We were told we were back to the levels prior to the closure, which is 2.2 million litres per week," the official told Reuters, though he cautioned that "everything is temporary" given tensions between Israel and Hamas.

Dror said he knew of no such open-ended deal. "I know of the defence minister's decision to allow a temporary shipment, and that the situation will be reassessed each week," he said.

According to Dror, the shipment included 2.2 million litres (581,000 gallons) of industrial fuel. Abu Sissi said he was told to expect to receive 900,000 litres (238,000 gallons) on Tuesday.

According to the EU official, between 700,000 litres (185,000 gallons) and 800,000 litres (211,000 gallons) of the fuel would be transferred on Tuesday, with the balance coming through on Wednesday and Thursday.

The bulk of Gaza's electricity, which comes from Israel and Egypt over cables, was not cut off, Israel said.