Hamas accused the rival Fatah movement on Monday of arresting 80 members of the Islamist group in a bid to sabotage Egyptian-brokered Palestinian reconciliation talks due to begin this week.

The issue underscores the challenges Cairo faces in trying to end Hamas-Fatah divisions and establish a unity government with a pro-peace policy that could lead to the lifting of an Israeli-led blockade on the Gaza Strip.

Ehab al-Ghsain, spokesman of the Hamas-run Interior Ministry in the Gaza Strip, said 80 Hamas members were detained in the West Bank, where Fatah holds sway, over the past few days.

He accused Fatah of "trying to foil" Egyptian-sponsored unity talks due to begin in Cairo on Wednesday.

A spokesman for West Bank security services loyal to Fatah's leader, President Mahmoud Abbas, said anyone harming Palestinian security was liable to detention and questioning.

Yasser Abed Rabbo, an Abbas confidant, said "there are no political arrests" in the West Bank, adding that individuals cleared of suspicions of security crimes could be released as dictated by law, but "not under Hamas pressure".

Hamas drove Fatah out of Gaza in June 2007 leaving Abbas with a truncated mandate in the Israeli-occupied West Bank.

Secular Fatah has mounted roundups of West Bank Hamas activists, and Hamas said more than 700 of its supporters have been jailed. Hamas has accused Fatah of reneging on promises to release many of them as part of a reconciliation process.

Some Hamas leaders have said the success, or even the start, of the Cairo talks depended on whether the detainees went free.

Abbas, who dissolved a government alliance with Hamas after the Gaza takeover, has called for a new union -- but on condition the Islamists submit to his authority.

Visiting Prague, Abbas said a Palestinian unity government must back his peace efforts with Israel -- which Hamas opposes -- "because any deviation from this principle will cause the world and international community not to recognise us".

Adding to tensions, the Hamas internal security service aired recorded confessions of former Fatah security officers in the Gaza Strip.

The ex-Fatah officers said they had been ordered by superiors in the West Bank city of Ramallah to gather information about the locations of Hamas institutions, tunnels, weapons factories and hideouts before Israel launched its assault on Dec. 27.

Hamas said the information was given to Israel, which used it during the Gaza war. Israel said it launched its campaign to end Hamas rocket salvoes.

Abed Rabbo said the confessions were coerced and part of a Hamas plot to poison the atmosphere before the Cairo talks.

"Hamas undermined the dialogue the first time and it is now inventing issues and stories inspired by its leadership in Damascus to undermine the second dialogue," he said, referring to Hamas's boycott of factional talks in November over Fatah's refusal to release jailed activists.