Israel reduced fuel shipments to the Gaza Strip on Sunday, Palestinian officials said, bringing promised pressure on the beleaguered territory's Hamas rulers after months of cross-border rocket attacks.

Mujahed Salameh, head of the Palestinian Authority's Petrol Agency, said diesel deliveries for Gaza's only power plant were 12% below normal and gasoline deliveries were half their normal level. He said the Israeli company that is Gaza's sole fuel supplier told him the Defense Ministry had ordered the limits.

The cutback followed Israel's declaration last month branding Gaza a "hostile territory." At the Cabinet's direction, a security panel drew up plans for reducing fuel and electricity to the coastal enclave, and Defense Minister Ehud Barak gave it final approval Thursday.

Israeli officials would not confirm that they had put the sanctions into effect. The Israeli fuel company, Dor Alon, said only that it was carrying out Defense Ministry orders but declined to reveal what those orders were.

At Gaza's main fuel depot, which receives diesel and gasoline pumped through pipes from the Israeli side, drivers of fuel trucks complained that they were unable to fill their tanks.

But no immediate impact was evident on the lives of Gaza's 1.5 million people. Officials in Gaza said the territory keeps about four days of fuel reserves.

How hard Israel intends to squeeze Gaza remains to be seen. The Israeli newspaper Haaretz quoted unnamed defense officials as saying fuel deliveries would be reduced by no more than 11% this week, far less than the cutbacks already reported by Palestinian sources. Later this week, Israel also is expected to impose limited cutbacks on the electricity it supplies directly to Gaza.

Salameh, whose agency is based in the West Bank but supervises fuel deliveries to Gaza, said that in addition to fueling Gaza's power plant, Israel supplies a special kind of diesel that a growing number of households and businesses use to run generators. Deliveries of that diesel were cut Sunday by about 40%, he said.

Jamal Khodary, head of Gaza's Popular Committee to Face the Siege, said the cutbacks would affect hospitals, water pumping stations, sanitation services and households.

"This will endanger lives," he said.

Palestinian Authority President Mahmoud Abbas' administration, which governs the West Bank and is bitterly at odds with Hamas, urged Israel to rescind the cutbacks.

Ten Israeli and Palestinian human rights groups petitioned Israel's Supreme Court on Sunday to issue an injunction against what they called collective punishment.

Israel has already shut Gaza's borders to most trade since Hamas, which calls for Israel's destruction, seized power in the territory in June. But those measures and frequent air and ground assaults into Gaza have failed to stop the rockets.

Deputy Defense Minister Matan Vilnai said Saturday that the measures were not punishment for the rocket fire but rather a step toward Israel's disengagement as an occupying power.