A top U.N. official said Tuesday there are "strong" suspicions that a militia loyal to Syria's President Bashar Assad carried out a massacre in the town of Houla which has sparked international condemnation.

"There is strong suspicion that the Shabiha were involved in this tragedy in Houla," U.N. peacekeeping chief Herve Ladsous told reporters at the U.N. headquarters.

Belgium declared the Syrian ambassador and two diplomats "persona non grata" Tuesday to protest the Houla massacre while raising the prospect of "a military presence" that was short of intervention.

Foreign Minister Didier Reynders said however that Syria's ambassador -- Mohammad Ayman Jameel Soussan -- could not be expelled immediately as he was also ambassador to the European Union.

The United States said Tuesday that it hopes the massacre in Syria sparks a "turning point" in Russia's reluctance to take tougher action against Syrian President Bashar Assad.

Washington welcomes the fact "that the Russians are willing to have a full investigation (of the massacre) because we think it's undisputable what that investigation is going to show," State Department spokeswoman Victoria Nuland said.

The head of Tunisia's ruling Islamist party, Rached Ghannouchi, said on Tuesday that the Arab Spring provided an opportunity to reconcile Arabic public opinion with the West.

He spoke at the opening of a conference in Doha on relations between the United States and the Muslim world, focused on the challenges created by the popular revolts that have swept the region and changed the political map.

Russia on Tuesday called for an "objective and impartial" U.N.-led probe into last week's massacre in the Syrian city of Houla that killed 108 people and left some 300 wounded.

"At this stage, there should be an objective and impartial investigation conducted under the auspices of the U.N. monitoring mission in Syria," the foreign ministry said in a statement after telephone talks between Foreign Minister Sergei Lavrov and international peace envoy Kofi Annan.

The long-overdue process of updating electoral lists in Gaza is expected to take six weeks, the head of the Palestinian Central Election Commission said on Tuesday.

The announcement was made a day after Hamas gave the CEC the green light to begin updating the lists for the first time in six years in a key step to paving the way for elections.

Syria's main opposition coalition called on Tuesday for a U.N. Security Council resolution authorizing the "use of force" and welcomed the expulsion of top diplomats from several Western countries.

After economic sanctions and the expulsion of top diplomats from several Western countries, the U.N. Security Council should "adopt a resolution under Chapter VII (of the U.N. Charter) allowing the use of necessary force in order to put a stop to the genocide and the murders committed by the regime's militias," the Syrian National Council said.

Egypt's Muslim Brotherhood presidential candidate Mohammed Mursi sought on Tuesday to reassure women and Coptic Christians, who fear a conservative Islamist could threaten their freedoms.

"Our Christian brothers, let's be clear, are national partners and have full rights like Muslims," said Mursi in a press conference.

Major Western powers said Tuesday they would expel Syria's diplomatic envoys in protest at the weekend massacre in the town of Houla, in which more than 100 people were killed.

The United States, Britain, France, Germany, Italy and Spain as well as Canada, Australia, The Netherlands, Bulgaria, Switzerland and Belgium announced decisions to expel ambassadors or top envoys.

Israeli President Shimon Peres said on Tuesday that Syrian President Bashar Assad has become the "murderer" of his people and they need help to free themselves from his regime.

"Their president, who is supposed to be the father of their nation, became their murderer," Peres told reporters during a joint press conference with visiting German President Joachim Gauck.