DAMASCUS, Syria - Palestinian Authority President Mahmoud Abbas and the exiled leader of the rival Hamas faction failed last night to resolve their differences over forming a unity government, dashing hopes for a quick end to deadly clashes between their supporters.

But Abbas and Hamas leader Khaled Mashaal said in a statement that they had "achieved major progress" during the meeting, and that they hoped to resume talks within two weeks.

"There are still points of disagreement, but we will try to resolve them through a national dialogue until we form a national unity government," Mashaal said during a joint news conference with Abbas in the Syrian capital, Damascus.

The two sides stressed that recent Palestinian fighting, which has killed at least 62 people, was unacceptable and pledged to exert efforts to avoid political friction.

"Palestinian bloodshed was considered totally prohibited, and we must exert all efforts to avoid frictions and internal clashes," Abbas said.

Both sides said differences remained, without providing details. The thorniest issues have been control of the two factions' security forces and Hamas' refusal to recognize Israel or commit to previous accords signed between Israel and the Palestinian Authority.

An official of Abbas' Fatah party in the Gaza Strip was optimistic about the meeting, saying Abbas and Mashaal had agreed to let an independent run the Interior Ministry, though they did not agree on who specifically should hold the powerful security post.

"I think some things were accomplished. Some issues were resolved and others remain problematic. That would need continuation of dialogue here in Gaza and mediation in Damascus," said Abdel Hakim Awad, Fatah's spokesman in Gaza.

He said differences also remained over how the official document laying out the new government would be worded.

The deputy head of Hamas' political bureau, Moussa Abu Marzouk, who attended some of yesterday's talks, said the one sticking point was the conditions under which Abbas would name a new prime minister for the unity government.

Despite the lack of agreement, he said the meeting "will send a message to the Palestinian people that the two sides are committed to continue dialogue."

Hamas, which controls the Palestinian parliament and cabinet, and Abbas' more moderate Fatah movement have been stuck in political deadlock since Hamas' victory in legislative elections last year. Abbas, who is widely seen as a moderate, was elected president separately.

The refusal of the Islamic extremists in Hamas to recognize Israel's right to exist led to Western sanctions that have paralyzed the Palestinian economy.

Abbas has been pushing Hamas for months to form a unity government of independent experts in hopes of ending the sanctions and has threatened to call early elections if the two sides can't agree.

Abbas, Israel and the international community also want Hamas to abide by past agreements signed between Israel and the Palestinians. Hamas has said it would be willing to respect only previous agreements it considers fair to Palestinians.

Syria hosts the exiled leaders of several Palestinian extremist groups, including Mashaal, who has lived in Damascus since 1997.

Yesterday's meeting took place after intense mediation by Syrian Vice President Farouk al-Sharaa, who met separately with Mashaal and Abbas.