Hamas warned on Tuesday that Palestinian president Mahmud Abbas's delay in easing sanctions on Gaza was putting at risk a landmark unity deal signed last week.

"The continuation of the punitive measures against our people in Gaza a month after the dissolution of the administrative council spoils the general atmosphere for reconciliation," a party spokesman said in a statement to Hamas media.

Islamist group Hamas last month agreed to dissolve its administrative council, seen as a rival government in Gaza, and return civilian power in the enclave to the Palestinian Authority a decade after seizing it in a near civil war.

Chief among their demands, however, was that Abbas drop a series of measures taken against Gaza.

Among these were reductions in energy payments for the territory which left its two million residents with only a few hours of mains electricity per day.

Hamas is due to hand over Gaza's border crossings by November 1 ahead of a full transfer of power by December 1.

The PA's top border official visited Gaza on Monday.

Previous reconciliation agreements between Hamas and Abbas's Fatah, based in the occupied West Bank, have collapsed over implementation of specific issues.

Security control of the Gaza Strip is expected to be a major stumbling block, with Hamas refusing to disarm its 25,000-strong armed wing.