JENIN, West Bank -- The Israeli army pushed into the Jenin Refugee Camp and Nablus in the West Bank early on Wednesday, AFP quoted Palestinian security sources as saying.

The sources said Israeli infantry units backed by tens of armored personnel carriers and tanks under cover of helicopter gunships had taken part in the dawn operation to reoccupy the Jenin town and its refugee camp.

The camp in March bore the brunt of the massive defensive shield assault on West Bank towns by the Israeli army.

The Palestinian sources said the Israeli army had towed at least five caravans by trailer into the refugee camp, suggesting it was going to stay for some time.

It later occupied the Palestinian self-rule town of Nablus, backed by armored vehicles and helicopter gunships, meeting no resistance, Palestinian security sources said.

Meanwhile, Israeli police arrested some 1,200 Palestinians in the past 24 hours after finding them on Israeli territory illegally, Israeli public radio reported.

Most were sent back to the West Bank, while the rest were detained for trial, the report added.