(Reuters) - Hamas suspended voter registration in the Gaza Strip on Monday in a setback to Palestinian plans for parliamentary and presidential elections and to forging unity with President Mahmoud Abbas´s Fatah movement.

Hamas, the Islamist group that seized the enclave from Fatah forces in 2007, cited the continued arrest of its members in the West Bank by security forces of the Palestinian Authority, which is led by Abbas.

The Central Election Committee had urged Palestinians in the West Bank and Gaza Strip to take part in voter registration, due to begin on Tuesday. Abbas was then expected to issue a decree setting a date for the long-delayed elections.

"Hamas decided to temporarily suspend the work of the commission until the obstacles are removed," Hamas spokesman Sami Abu Zuhri said.

"We are still committed to reconciliation and to holding elections but aggressive security measures in the West Bank would lead to an election outcome favouring (Fatah)," he said.

Hamas members in the West Bank, Abu Zuhri said, could not register to vote or monitor the election committee´s activities because of the security crackdown.

Ahmed Assaf, a Fatah spokesman in the West Bank, accused Hamas of retreating from Egyptian-brokered unity deals.

"It means Hamas did not want an election to be held and did not want to move ahead toward reconciliation," Assaf said.

Fatah also accuses Hamas of holding members of the group in its Gaza jails. Disputes over political detentions by both sides have plagued efforts at unity.

Hani Habib, a political analyst in Gaza, called Hamas´s move "a real setback. It bolsters doubts by the Palestinian public that neither side has good intentions to end the division."

(Additional reporting by Ali Sawafta in Ramallah; Editing by Janet Lawrence) (© Thomson Reuters 2012. 07/02/12)