The Hamas government in the Gaza Strip said on Monday it has "temporarily" halted voter registration just over a month after granting the electoral commission permission to work.
The decision was criticised in the West Bank, with Fatah official Azzam al-Ahmed saying that the Hamas decision "halts the reconciliation" between the rival Palestinian movements.
In a statement, Hamas spokesman Sami Abu Zuhri cited various "obstacles" that needed to be resolved before the electoral commission could resume its work.
"Hamas and the government in Gaza have provided the Central Election Commission (CEC) with all the facilities required for it to carry out its role with ease," he said.
"But there are many issues that represent obstacles," he said. "Therefore Hamas has decided to temporarily suspend the registration process until an agreement between the parties involved to remove the obstacles."
The statement lists a variety of alleged obstacles, including the arrest of Hamas members in the West Bank and a failure to carry out registration in the Palestinian territories and abroad at the same time.
It also says no agreement has been reached on dealing with the "large number" of unregistered Palestinian voters in the West Bank and Gaza who do not have identity cards.
And it criticises the selection of election commission officials, as well as the civil society bodies that are meant to oversee the registration process.
Ahmed, who has handled Fatah's negotiations with Hamas as the rival movements sought to mend a years-old rift, said the decision "halts the reconciliation and blocks it."
But he expressed hope that Hamas would "review its decision and stop interfering in the work of the electoral commission and comply with the text and the spirit of the reconciliation agreement."
The decision was also criticised by Hanan Ashrawi, a member of the Palestinian Liberation Organisation, who said in a statement "it does not serve efforts to achieve national reconciliation."
"People must be able to have their say," she added.
Hamas granted the commission permission to begin its work in Gaza on May 28, with the goal of updating a voter register that has been untouched since 2006.
The voter registration is part of preparations for legislative and presidential elections called for under a reconciliation deal signed by the rival Palestinian movements Hamas and Fatah last year.
Ahead of the elections, the two movements were supposed to agree on a consensus government of independents to pave the way for a vote, but talks on the composition of the government have broken down on several occasions.
The CEC reopened its Gaza offices in January but could not begin work on updating the voter lists without Hamas's permission.
After receiving permission to begin its work in late May, it started opening offices and recruiting employees and had been due to start registering individual voters on Tuesday.