Israel approved Thursday a plan to start punitive disruptions of the Gaza Strip's scarce supplies of electricity in response to rocket attacks from the Palestinian territory.

Israeli officials, noting that Palestinian militants fire rockets across the border almost daily, said the sanctions could start anytime. The plan calls for initial power cutoffs of 15 minutes, followed by increasingly longer ones each time more rockets fall.

Gaza's 1.5 million people get 60% of their electricity from Israel, which pulled its troops and settlers from the territory in 2005 but still controls Gaza's borders. Although many buildings have backup generators, power cutbacks would add to the impoverished coastal strip's hardships.

Since Israel's government began debating the sanctions, U.N. Secretary-General Ban Ki-moon and numerous international organizations have warned against what they say is unfair collective punishment.

Yet Israeli leaders defended the planned cutbacks in the hope that Gaza's ruling Hamas movement would respond by reining in the militants, whose crude, short-range rockets have terrorized Sderot and other border communities in Israel. The Israeli military has proved unable to stop the assault.

Hamas has defended the rocket fire, which comes from smaller militant groups such as Islamic Jihad, as a response to what it calls Israeli aggression. A Hamas spokesman, Taher Nunu, called Israel's decision to cut electricity "a real crime." Shortly afterward at least three rockets fell harmlessly near Sderot.

Hamas' violent takeover of Gaza in June prompted Israel to close the territory's borders to nearly everything except fuel, water, electricity and humanitarian relief. Last month the Cabinet declared Gaza a "hostile territory," clearing the way for a security panel to draft a plan for tighter sanctions. Defense Minister Ehud Barak's approval Thursday set the plan in motion.

"Because this is an entity that is hostile to us, there is no reason for us to supply them with electricity beyond the minimum required to prevent a crisis," Deputy Defense Minister Matan Vilnai told Army Radio.

Israeli officials said they would not cut power to hospitals.

The sanctions plan also calls for cutbacks in Israeli supplies of fuel to Gaza as part of a long-term disengagement from the territory, but officials said they were focusing first on reducing the supply of electricity.

Israeli commentators said the government was moving gradually, testing how thoroughly it could isolate Gaza without widespread international protest. As an occupying power, Israel would be obligated under international law to provide essential services to Gaza and restricted in its use of sanctions.

"The measures Israel seeks to implement are based on the legal assumption that Gaza is no longer under occupation since the Israeli troop pullout," Yuval Shani, an international law expert, told Israel Radio. "That position is not shared by most countries or even most legal experts. Even if some of the measures will be legally defensible, there will be a diplomatic price."