JEDDAH, Saudi Arabia (Reuters) – U.S. allies Egypt and Saudi Arabia will on Tuesday discuss Syria’s standoff with the United Nations a day after U.N. officials asked to meet Syria’s president over the murder of a former Lebanese premier.

Diplomats said the leaders of both countries would discuss how to press Damascus into fully cooperating with the United Nations, especially after a senior Syrian politician said President Bashar al-Assad had threatened ex-Prime Minister Rafik al-Hariri months before his killing.

Egyptian President Hosni Mubarak would hold talks with Saudi King Abdullah in the Red Sea city of Jeddah, Saudi officials said. “Syria is on the agenda,” one official said.

Egypt’s state-owned Al Ahram newspaper also said the talks would include “the Syrian file in light of recent changes.”

Middle East political heavyweights Saudi and Egypt are worried about the possible fallout of Syria’s intransigence.

A U.N. resolution in October threatened further action against Syria if it did not cooperate, and this could lead to sanctions either against individuals or the country as a whole.

Other topics up for discussion will be Iraq, the Israeli-Palestinian conflict and regional relations.

The U.N. probe has already implicated senior Syrian officials and their Lebanese allies in the truck bombing that killed Hariri and 22 others in Beirut on February 14.

Last week, former Syrian Vice President Abdel-Halim Khaddam said Assad had delivered “very, very harsh words” to Hariri before the bombing. On Monday, the U.N. commission probing the murder said it had asked to interview Assad and his Foreign Minister Farouq al-Shara.

Khaddam’s remarks are likely to intensify international pressure on Syria’s government.

A U.N. interim report in October said Shara had given the commission “false information” by describing a meeting between Assad and Hariri as friendly, contrary to several Lebanese witnesses who said the president had threatened Hariri.

Syria has already strongly denied any role in the murder and dismissed as politically motivated the findings of the U.N. probe. Hariri’s killing drew international condemnation which forced Damascus to withdraw its troops from Lebanon in April.

The United States — which accuses Damascus of not doing enough to stop foreign fighters from crossing into Iraq and of supporting Palestinian and Lebanese militants — has also piled pressure on Assad’s government to cooperate with the United Nations.