Syria, which has strained ties with the Western-backed government of Lebanese Prime Minister Fouad Siniora, had said it would wait until Lebanon elects a new president before inviting Beirut and Riyadh to the March 29-30 summit. Saudi Arabia also backs Siniora, who is an opponent of Syria.

Syria has invited all other Arab League members, according to Lebanese politicians.

Egyptian state news agency MENA reported that Moualem, speaking late on Tuesday, said that "if a Lebanese president is not elected before the Arab summit, then Lebanon will choose who will represent it".

Analysts said this might trigger friction since Siniora should be the official representative of Lebanon in Damascus, which would be bitter pill for the Syrians to swallow.

Moualem, in Cairo for a two-day meeting of Arab foreign ministers to prepare for the summit, would not be drawn on to who the Lebanon invitation would be sent. Political sources said the Syrians would like other than Siniora to attend.

A Lebanese official said Siniora might not go if many Arab leaders stayed away. Diplomats in the region say they expect the leaders of heavyweights Saudi Arabia and Egypt, as well as Jordan, to stay away unless Lebanon elects a president by then.

The summit is expected to focus on Lebanon, which has been without a president since November due to a power struggle, and on the Gaza Strip, where an Israeli offensive killed more than 120 Palestinians.

Syria expects at least 12 of 22 heads of state to attend, including those of Qatar, the United Arab Emirates, Oman, Tunisia, Algeria and Libya as well as the Palestinian president.

Saudi Arabia's relations with Syria deteriorated after the 2005 assassination of its main Lebanese ally, former Prime Minister Rafik al-Hariri. Many in Lebanon and the Arab world blamed Syria for the killing. Damascus denies any involvement.

Arab League mediation has so far failed to break the impasse, which has forced the Lebanese presidential vote to be postponed 15 times since September. The election is now due on March 11. (Writing by Cynthia Johnston; Editing by Ibon Villelabeitia)