Rival Palestinian factions have so far failed to overcome obstacles in reconciliation talks which they hope will lead to a unified governing body for the Gaza Strip and the West Bank, officials said on Friday.

President Mahmoud Abbas's Fatah movement has insisted during Egyptian-hosted talks taking place in Cairo that rival Islamist group Hamas must "abide" by existing peace agreements signed with Israel but Hamas has refused to make such a commitment.

Hamas proposed using the word "respect" instead of "abide" but this falls short of satisfying the conditions set by United States, Israel and Western countries.

The agreements and commitments with Israel were signed by the Palestine Liberation Organization, now headed by Abbas.

Hamas, the Islamist movement which won a parliamentary election three years ago, has controlled the Gaza Strip since a brief, bloody civil war in 2007. Abbas's Palestinian Authority holds sway in the occupied West Bank.

Israel, the United States and Western countries have refused to recognize Hamas's control of Gaza. Israel, which has imposed a blockade on the coastal territory, has demanded an end to Hamas rule before it considers easing its restrictions.

Egyptian intelligence chief Omar Suleiman met Fatah and Hamas leaders late on Thursday to try to narrow differences, officials said.

Abbas, talking to reporters in the West Bank town of Ramallah, said negotiations "had encountered difficulties."

"BALANCED FORMULA"

"It requires effort and genuine will in order to reach national reconciliation. We don't want to talk about obstacles. We hope the talks will succeed," Abbas said.

Hamas delegate Fawzi Barhoum told Reuters from Cairo that differences remained. "We have not yet agreed to the agenda of the new government and there are obstacles that need to be removed to reach a balanced formula," he said.

Fatah and Hamas formed a short-lived unity government in 2007, with a platform saying it would "respect" the PLO's previous commitments. But it was not enough to bring an end to the international embargo on the coastal territory.

Hamas, whose founding charter calls for Israel's destruction, has said it could accept a Palestinian state in lands Israel captured in a 1967 Middle East war, but it has refused to give Israel formal recognition.

"An internal agreement does not require the recognition of Israel or dealing with foreign conditions," said Taher el-Nono, a spokesman for Hamas in Gaza.

Hamas has insisted on a right to all of Palestine, including what is now Israel, but has said it could commit to a long-term truce lasting 15 to 20 years.

Hamas says the continued detention of hundreds of Hamas supporters by Fatah in the West Bank is another obstacle to the work of five committees assigned to reach a deal.

Security services loyal to Abbas deny holding anyone on political grounds and say they freed 45 Hamas supporters on Thursday. A Hamas official confirmed 30 releases but said eight more supporters were detained on Thursday night.

"The issue has become the biggest obstacle facing chances of success of the dialogue and it cast its shadow over the entire discussion. We will never skip over this point," Barhoum said.