Hatem Moussa, Associated Press
Palestinians hold candles during a demonstration against restrictions by Israel that led to power cuts in Gaza City on Monday.

JERUSALEM — The Israeli defense minister, Ehud Barak, said Monday night that he was lifting some of the restrictions imposed on Gaza and that on Tuesday he would allow delivery of a week's supply of industrial diesel for the local power station, as well as 50 trucks of food and medical supplies.

The decision came as aid officials warned that Gaza, gripped by fuel and electricity shortages, was two or three days away from a health and food crisis, and as international alarm mounted and criticism of Israel intensified.

Israeli officials said they had made the decision after reviewing the situation in Gaza, which they had insisted they would not allow to become a humanitarian crisis and after seeing a reduction in rocket fire. They denied international pressure was a factor.

Barak ordered the closing of border crossings into Gaza on Thursday night, halting all imports, in response to last week's intense rocket fire against Israel by militant groups in the Gaza Strip, which is run by Hamas.

No goods have been allowed in since, and Gaza shut down its only power station on Sunday as the diesel needed to fuel it ran out.

Israel and Egypt continued to provide electricity to Gaza by cable, but the closing of the power station cut Gaza's supply by at least a quarter, or by as much as 43 percent, according to different estimates of the area's needs. By Monday night, parts of Gaza City, where about a third of Gaza's 1.5 million people reside, had been blacked out for 24 hours.

The U.N. Relief and Works Agency, which provides assistance to Palestinian refugees and their descendants, announced Monday that it would have to suspend its food aid to 860,000 Gaza residents by Wednesday or Thursday if the crossings were not reopened, because it was running out of the nylon bags it uses to measure out and distribute staples like flour.

Oxfam, the international aid agency, warned in a statement issued Monday afternoon that Gaza's water and sewerage systems were "a matter of hours from almost total shutdown as stocks of fuel to run vital pumps runs out."

Mahmoud Daher, a health officer for the World Health Organization in Gaza, said on Monday that there was a shortage of more than a hundred types of medications, and there were no spare parts to fix broken generators.