JERUSALEM The European Union warned Israel on Monday against imposing "collective punishment" on the 1.5 million Palestinians in the Gaza Strip by reducing the territory's fuel supplies.
Israel began implementing the sanctions on Sunday in what it said was a response to Palestinian rocket fire on Israeli towns from the Hamas-controlled coastal enclave.
"We understand the distress that is caused in Israel by the continuing rocket attacks from Gaza," Benita Ferrero-Waldner, the EU's commissioner for external relations, told Reuters after her meeting with Israeli Prime Minister Ehud Olmert in Jerusalem.
But she said the new sanctions "will have very grave consequences for the life of the local population" and serve to bolster Hamas and other militant groups. "There should not be collective punishment," she added.
Israeli defence officials said fuel supplies would be reduced by up to 14 percent, depending on the type of fuel. Electricity cuts would be limited to about one percent for 15 minutes a day in certain areas.
There was no obvious impact immediately on Gaza's electricity supply.
Palestinian officials said on Sunday that deliveries of fuel oil for Gaza's power station, as well as of diesel and petrol, were being cut from a quarter to a half.
An official from the European Union, which funds fuel oil to Gaza's only electricity generating plant, said deliveries to the plant were down by about a quarter on Sunday but that it had stocks for about seven days of operation.
Israeli defence officials said the power plant would receive enough fuel to continue operating.
Hamas, which seized the Gaza Strip by force from rival Fatah in June, condemned what it called Israel's "blackmail" and forecast an "explosion" that would have an effect across the Middle East.
Olmert, weakened by last year's war in Lebanon, faces opposition within his cabinet over peace talks with Palestinian President Mahmoud Abbas, whose secular Fatah faction remains in power in the occupied West Bank.
"This development would certainly only play into the hands of those who are trying to derail the ongoing negotiations between the parties," Ferrero-Waldner said.
Infrastructure Minister Binyamin Ben-Eliezer said on Israel Radio: "What is the alternative?... Our duty first and foremost, despite all the name-calling, is to protect our people."
Makeshift rockets have killed two Israelis this year.
Palestinians argue that, as Israel continues to control Gaza's frontiers since withdrawing troops in 2005, it still has the obligations of an occupying power under international law to ensure the welfare of the population.
Olmert has said he will not allow a "humanitarian crisis". Officials said the fuel cuts were designed not to affect medical and other vital facilities in Gaza, which Israel last month declared to be an "enemy entity".
(Additional reporting by Dan Williams)