BIR ZEIT, West Bank — At 26, Saed Qasrawi is among the oldest students at Bir Zeit University in the West Bank.

The leading Hamas activist has been enrolled for eight years, but he has been unable to complete his undergraduate engineering program because he keeps getting detained by Palestinian security forces before final exams.

This year, Qasrawi and more than a dozen other supporters of the Islamic militant group tried a new tactic. Since May 5, they've remained on campus — a sanctuary considered off limits to the security forces — to evade arrest.

Even with the tests over, the students are staying on, sleeping on mattresses in the enclosed foyer of the campus ATM machine because they fear they'll be picked up if they leave.

Hamas student activists say President Mahmoud Abbas' security forces keep harassing them, despite new attempts by him and his Hamas rivals to reconcile and end five years of separate governments in the West Bank and Gaza Strip.

Human rights groups say each side continues to go after the other's supporters, even though a reconciliation agreement calls for an end to political arrests. Dozens have been detained.

The reconciliation agreement, reached in principle more than a year ago, envisions the formation of an interim unity government that would prepare for presidential and parliamentary elections. The deal has not been carried out, though the two sides made another attempt earlier this week by setting a new timetable that would see the unity government formed in early June and elections six months later.

Hamas seized control of Gaza from forces loyal to Abbas in 2007, leaving Abbas governing only in the West Bank.

The Western-backed Abbas says he shuns violence and hopes to negotiate the terms of a Palestinian state with Israel. Hamas, which killed hundreds of Israelis in shootings and bombings in the past, refuses to drop the option of armed struggle and says negotiations with Israel are a waste of time.

After losing control of Gaza, Abbas dismantled Hamas institutions in the West Bank. In Gaza, Hamas silenced political opponents, including Abbas' Fatah movement, while setting up a stable government.

Halting political arrests was to have been a first step toward reconciliation.

"Unfortunately, both sides continue to arrest people and the same goes for summoning" for interrogation, a harassment tactic that forces activists to spend hours at a time at police stations, said Mustafa Barghouti, who heads a committee that is supposed to monitor the situation.

Currently, 68 Hamas activists are being held in Palestinian lockups in the West Bank, compared to several hundred at a time in previous years, said Ahmed Attoun, a Hamas lawmaker.

In Gaza, more than 20 Fatah members are being held and others are being summoned repeatedly for interrogations, said Fayez Abu Itta, a local leader of the movement.

Politically active university students in both territories said they are being harassed by the security forces, though there has been no formal ban on Hamas or Fatah to compete in student council elections.

In the West Bank, Hamas blamed its recent losses in elections in four of the main universities, including Bir Zeit, on intimidation by the security forces. Before 2007, Hamas had a strong presence in the universities, running several councils, including that of Bir Zeit, but since the start of the crackdown has not be able to regain control.

"They are trying to weaken the movement, particularly in the universities because the students are very energetic," said Mohammed Qadoumi, 22, a pro-Hamas student at Bir Zeit. "The security forces told us 'we want to erase your presence,'" he charged.

Ishaq Mukhmar, a Fatah student leader in Gaza, also complained of harassment, including banning campus activities of Fatah's Shabiba youth movement. "We can have some activities here and there, but we can't say we are allowed to work freely," he said.

In the West Bank, Barghouti's "Freedom Committee" negotiated an agreement with the security forces earlier this year that student activists would not be arrested, said Qasrawi, the Hamas leader at Bir Zeit University. Despite that, three weeks ago, two of his fellow activists were taken from their homes, Qasrawi said.

In response, he and 14 other pro-Hamas students, all wearing black T-shirts with the slogan "Sit-in until the end of arrests," took refuge on campus.

Since May 5, they've been sleeping next to the ATM or on mattresses outdoors, showering in quarters used by private security guards and getting meals from the university cafeteria. Seven of the students believe they are wanted by the security forces, and eight said they've joined the protest to show support.

"Staying here was the only way to avoid detention during the exams," said Qasrawi, who leads the Hamas student bloc on campus. He said he was arrested at the start of final exams five times over five years and still has a year of studies left.

Adnan Damiri, a spokesman for the security forces, denied any of the 15 are wanted. By alleging harassment, they are trying to make excuses for losing the student elections, he said. "We don't target them," he said.