A Palestinian leftist official on Thursday criticized Islamic Hamas movement's combination between internal authority and fighting against Israel.

"Hamas has to select either to stick to the Palestinian resistance program or to have a share in the power cake," said Rabah Muhana, a leader of the Popular Front for the Liberation of Palestine (PFLP).

"Making harmony between the method of resistance and the ruling is a wrong tactic proved its failure and was a key reason for the inter-Palestinian conflict," Muhana added.

Hamas won the parliamentary elections in 2006 and formed a government in the Palestinian territories but Israel and the Western countries isolated that administration since Hamas doesn't recognize Israel and the peace deals with it.

"Hamas did not take into consideration that the Palestinian (National) Authority (PNA) is bounded by Oslo agreement and that it will come under pressure to abide by Oslo's concessions," Muhanna said, referring to the Israeli-Palestinian main peace accord of Oslo, 1993.

A year after it won the elections, Hamas routed security forces of president Mahmoud Abbas, ousted his Fatah movement and seized control of the Gaza Strip, cutting the political ties with the West Bank where Abbas boosted his rule by forming a Western-backed government.

As Egypt sponsors reconciliation dialogue between Hamas and Fatah, Hamas refused to join or accept the formation of any unity government that deals with Israel directly, widening differences with Fatah.