Hamas said Tuesday Palestinian President Mahmoud Abbas's security forces had arrested 170 of its members in the West Bank in the past four weeks in a campaign that could hamper Egyptian-sponsored unity talks.

Sami Abu Zuhri, a Hamas spokesman, said the detentions could "poison the atmosphere and block the way" toward reconciliation with Abbas's Fatah faction, which lost control of the Gaza Strip to the Islamist group in fighting in June 2007.

The latest arrests, Abu Zuhri said, raised the number of Hamas members detained by forces loyal to Abbas to at least 400 in the past year.

He urged Egypt to press Abbas to halt the campaign before Palestinian factions convene in Cairo on November 9 to discuss reconciliation.

Hamas, Fatah and other groups have welcomed Egypt's presentation of a draft reconciliation paper, but some factions have called on Cairo to make amendments to the document.

Fatah spokesman Fahmi Zarir, denying any political motive behind the arrests, said security forces in the West Bank were trying to restore law and order.

Fatah says more than 120 of its members in the Gaza Strip are in Hamas-run jails.

Human rights groups have accused security forces loyal to Hamas and Fatah of abuses over the past year, including extra-judicial arrests and torture.

The head of the European Union training program for Abbas's police force in the West Bank, Colin Smith, said security detainees should be dealt with through the criminal justice system.