Aljazeera’s correspondent in Palestine reported on Friday that Israeli forces were conducting search operations in Jenin, tracking “wanted activists”.
Clashes between Al-Aqsa Martyrs Brigade and Israeli forces erupted later in the day.
Meanwhile, Israel has indicated that it would allow Palestinian leader Yassir Arafat to take part in mourning for his late sister.
On Thursday, about 2000 people were mourning the death of Arafat’s sister, Yussra Al-Qidwa. She died one day earlier in Gaza at the age of 77, but Arafat was confined to his base in the town of Ram Allah.
Palestinian security chief Muhammad Dahlan met with Israeli Defence Minister Shaul Mofaz to discuss the siege of Arafat and “humanitarian question” of him travelling to Gaza.
"Mr Mofaz promised to speak with Prime Minister Ariel Sharon and will convey the response to this request at their next meeting," likely to be held Friday or Sunday, the spokesman said.
Israel considers Arafat an obstacle to peace and has kept him confined to his compound in Ram Allah since December 2001 – except for a brief period of freedom last year. In the past Israel has said it would permit Arafat to leave, under the condition that he would not be allowed back.
In other developments:
The official Israeli position is that Arafat is free to leave Ram Allah for Gaza or abroad, but is not sure he would be allowed back in.
A member of Islamic Jihad escaped from a Palestinian jail in the West Bank city of Jericho, an official from the group said on Friday.
The detainee was identified as Ala Sawar, the official said, on condition of anonymity.
He did not say when Sawar escaped, but added nine other members of the group were detained in Jericho "without reason."
Earlier this month, a high ranking Palestinian official said that 19 Palestinians wanted by Israel were jailed in Jericho in late July as part of an agreement between Yassir Arafat's Palestinian Authority (PA) and Israel.
The move was part of efforts by the PA to jail and disarm resistance fighters as required by the US-backed roadmap for peace.