The only electrical plant the Gaza Strip began shutting down today because Israel has blocked its fuel shipment.
A UN agency and human rights groups condemned Israel, but Tel Aviv said Palestinian militant groups that fire rockets at southern Israel every day are to blame.
Israel sealed all crossings into Gaza last week because of am upsurge in rocket attacks.
Several weeks ago Israel reduced the fuel supply as a pressure tactic. In addition to the fuel it receives from Israel to power its electrical plant, Gaza gets about two-thirds of its electricity directly from Israel.
Israeli officials said that supply would not be affected.
Power cuts began in parts of Gaza City today.
Shlomo Dror, spokesman for Israel's Defence Ministry, said Gaza has enough fuel and accused Palestinian officials of trying to create the impression of a crisis that did not exist.
While residents of Gaza City began stocking up on batteries candles and basic foods, grocery store owner Sami Mousa many cannot afford the added cost.
AP