Israeli forces raided the West Bank offices of three Palestinian non-governmental organisations overnight, confiscating computers and other material, one of them said on Tuesday.
"At 3:00 am (0100 GMT) this morning, 11 December 2012, the Addameer Prisoner Support and Human Rights office was raided by the Israeli Occupation Forces (IOF)," the group said on its website.
"Four laptops, one hard disk and a video camera were taken among other materials. The IOF destroyed the office," the group added, saying desks and "ransacked filing cabinets" were left scattered after the raid.
"At this moment, we are not clear as to what has been confiscated," it said, adding the raid was the first time the group's Ramallah offices had been targeted by Israeli forces since 2002.
Addameer said the military also ransacked the Ramallah offices of the Union of Palestinian Women's Committees and the Palestinian NGO Network.
An army spokeswoman told AFP that the groups were linked to the leftist Popular Front for the Liberation of Palestine (PFLP), which Israel considers a terrorist organisation.
"Soldiers searched several offices in Ramallah which were affiliated with the Popular Front organisation," she said.
"We don't know that they were Popular Front offices, but they were affiliated with a terror organisation," she said when asked to elaborate.
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Last month the PFLP's armed wing claimed an anti-tank missile attack on an Israeli army jeep patrolling the border with the Gaza Strip, wounding four soldiers.
It has also said it repeatedly fired rockets into southern Israel.
Addameer (Arabic for conscience) is a prominent Palestinian NGO campaigning for the rights of Palestinians held in Israeli jails.
The group condemned the attack saying it "sees it as an attempt to cripple solidarity with the prisoners movement."
Palestinian government spokeswoman Nour Odeh said the raid was part of an Israeli policy of "pursuing human rights activists and defenders of the law who expose... systematic and continued Israeli violations."
Amnesty International said the raid was "part of a wider onslaught against Palestinian human rights and civil society organisations and their staff."
"It's a pattern of harassment which seems designed to curtail their vital work," the London-based rights group said in a statement.
Although the West Bank city of Ramallah nominally falls under full Palestinian administrative and security control, Israeli forces frequently carry out raids in the city and its surroundings.