UPDATE 1-Israeli tanks open fire in Jenin camp

JENIN REFUGEE CAMP, West Bank, April 17 (Reuters) - Israeli tanks fired heavy machineguns inside Jenin's refugee camp on Wednesday and the army warned residents combing the rubble of their homes that a curfew remained in force.

Earlier, witnesses in Jenin had said about 50 Israeli tanks had left the camp and the surrounding West Bank town, two days after Israeli Prime Minister Ariel Sharon had said the army would pull out "in a couple of days".

It was not immediately clear what had prompted the tanks still in Jenin to open fire in the camp's smashed streets.

Earlier in the afternoon, hundreds of Palestinians had poured back into the refugee quarter from the town, many of them residents who had fled fierce fighting between the Israeli army and Palestinian militants that abated at the weekend.

Although a general curfew has prevailed for over a week, it appeared not to have been strictly applied in parts of the town and camp over the past three days, with many more people on the streets and even some local cars moving around.

Before Wednesday's tank shooting started, civilian medics had been digging in the rubble that was once the camp's main square, uncovering what looked like a large human bone.

When the tanks opened up, the medics hurriedly covered up what they had found with boards and fled into a nearby alley.