I have to be much more cautious now. I'm afraid to speak freely, said Ms Obeiyat, whose father is a member of Hamas.

She was first arrested in 2002 for allegedly trying to stab an Israeli soldier in retaliation for Israel's killing of her brother and uncle. In 2009, months after serving out her original sentence, she was arrested again for violating the travel restrictions imposed on her by Israel. Sentenced to three more years in jail, her term was cut short by last month's agreement.

To some, her worries may verge on paranoia. But history suggests her fears are not groundless.

Israel makes no secret of arresting, deporting or killing those Palestinians it says take up arms after their release under such deals. But Palestinians say many a freed prisoner has fallen victim to score-settling by Israel and its liberal use of extralegal military powers and secretive military tribunals.

Yesterday, Israeli soldiers ransacked the West Bank home of one of the prisoners released in the recent swap, Duaa Al Jayousi, who had been serving multiple life sentences. She was not arrested but the Palestinian news agency Ma'an reported soldiers told her that she was being watched.

These people are flagged for monitoring by the Israelis when they are released, which means their release is not the end of the story, said Zakaria Al Qaq, a Palestinian expert on security issues, describing safe-conduct guarantees stipulated by Palestinian-Israeli prisoner swaps as paper thin.

Jawad Amawy, the legal director at the Palestinian Authority's ministry of detainees and ex-detainees affairs, said that since the beginning of the second intifada in 2000, about 70 Palestinians freed under such prisoner-release agreements have been rearrested for highly questionable reasons.