The US Secretary of State, Colin Powell, has told Israel it should stop its incursions into Palestinian towns "without delay" after the bloodiest day yet since the military operation began. But fighting between Palestinians and Israeli troops is raging through densely populated refugee camps in the West Bank, with reports of heavy loss of life in the northern town of Jenin. Residents at the Jenin refugee camp said they feared a "massacre" was taking place, and one Palestinian fighter said he had counted 30 dead bodies. Israeli air force commander Dan Halutz told a news conference that seven soldiers had been killed over the past two days in Jenin. Fierce clashes were also reported in Nablus, the biggest Palestinian city in the West Bank, where Israel forces attacked targets in its historic market area and surrounded the Balata refugee camp.