JERUSALEM (AFP) - Israel's deadly offensive on Hamas targets in its Gaza Strip stronghold entered its second week on Saturday, with truce efforts stalled. The following are factors in what United Nations agencies say is a mounting humanitarian crisis in the impoverished territory, home to 1.5 million Palestinians. There is an airstrike about every 20 minutes on average, more at night. The Israeli bombardment has caused widespread destruction, with over 600 targets hit, including roads, infrastructure, government buildings and police stations. The health system is overwhelmed after already having been weakened by 18 months of an Israeli blockade. Besides at least 436 Palestinians being killed, nearly 3,000 people have been wounded since Dec 27, according to Gaza medics. About 250,000 people have no electricity. Gaza's only power plant shut down on Dec 30 for the sixth time since Nov 5 for lack of fuel and spare parts. The water system provides running water once every five to seven days. Forty million litres of raw sewage are dumped into the Mediterranean every day. Heating fuel and cooking gas are no longer available in the market. Sewage has been pouring into the streets after the main sewage pipeline was hit on several occasions. Eighty percent of Gaza's population depend on humanitarian aid. There are shortages of flour, rice, sugar, dairy products, and canned foods. Israel has allowed in a daily average of about 60 truckloads of vital supplies since Dec 27. The figure is up from recent months, but far below the 475 average prior to June 2007. Pipelines at the Nahal Oz terminal that usually handle all of Gaza's fuel imports have remained closed since the start of operations. Schools are closed, but many are used as shelters by people who have fled their homes. Banks are closed because of cash shortages. Meanwhile, Japan pledged 10 million dollars in humanitarian aid Saturday to the Gaza Strip, which has been pounded by Israeli airstrikes for more than a week, officials said. Prime Minister Taro Aso made the offer in a telephone conversation with Palestinian President Mahmud Abbas, the government officials said. Abbas, who has not had power over the Gaza Strip since the Hamas movement gained control of the region in June 2007, thanked Japan, the officials said. On Wednesday, Aso asked his Israeli counterpart Ehud Olmert by telephone to halt the airstrikes and allow transportation of humanitarian aid to Gaza. In response, Olmert said the attacks against Hamas were being made in self-defence and promised cooperation over delivery of humanitarian aid to Gaza, according to the Japanese Foreign Ministry. Japan, which relies on the Middle East for nearly all of its oil, has traditionally kept good relations with Arab nations and Iran.