Turkey will close its border crossings with neighboring strife-torn Syria on Wednesday until further notice, a Turkish official told Agence France Presse.

"We have taken such a measure for our citizens for security reasons," said the official. "This is an open-ended measure and the reopening depends on the developments on the ground."

Progressive Socialist Party leader MP Walid Jumblat stressed on Wednesday that the current cabinet will not collapse until the reasons behind its formation fall.

“There will be no escalation, the political reason behind the formation of the cabinet still exists,” Jumblat told al-Akhbar newspaper.

Israeli Foreign Minister Avigdor Lieberman said Wednesday that Israel will act immediately if it discovers that Syria transferred chemical or biological weapons to Hizbullah.

Lieberman told Israel Radio: "For us, that's a casus belli, a red line."

Foreign Minister Adnan Mansour revealed on Wednesday that he sent a memorandum to Syrian Ambassador Ali Abdul Karim Ali demanding his country to avoid the recurrence of any border incidents.

Mansour made the revelation to reporters ahead of a cabinet session at the Grand Serail and following two days of harsh criticism by the March 14 opposition on his procrastination in delivering a letter of complaint on Syria’s violations of Lebanese territories in compliance with President Michel Suleiman’s request.

The Syrian army and rebels deployed more forces in and around Aleppo on Wednesday as a "decisive" battle for control of the country's second city raged, activists and regime sources said.

"Hundreds of rebels from all over the north of Syria are arriving in Aleppo, which appears to have become the decisive battle," a journalist for a Syrian newspaper working in the city told Agence France Presse.

President Michel Suleiman is throwing on Wednesday an Iftar banquet for Lebanese officials, spiritual leaders and foreign diplomats during which he is expected to reiterate the need for dialogue.

Media reports said Suleiman’s speech will focus on the latest developments in the region and the national dialogue session that was postponed to August 16 after the March 14 opposition coalition boycotted this week’s all-party talks.

The head of the Syrian embassy in Cyprus, Lamia al-Hariri, has defected to Qatar, pan-Arab satellite television networks reported on Tuesday.

Al-Jazeera television said in a brief report that Hariri, the charge d'affaires, had "announced her defection in Cyprus," while Al-Arabiya said she had arrived in the Gulf state of Qatar.

Dozens of people protested at the Russian embassy in Beirut on Tuesday, denouncing Syrian regime "massacres" while calling on Russia and China to change their positions on the crisis.

The protesters -- both Syrians and Lebanese -- held up posters denouncing the violence in neighboring Syria, where rights activists say more than 19,000 people have been killed in a 16-month uprising.

A Russian naval flotilla of warships destined for the Syrian port of Tartus has entered the Mediterranean, Russia's defense ministry said Tuesday.

"The Russian ships today passed the Strait of Gibraltar and entered the Mediterranean at 1200 GMT," said a defense ministry spokesman, quoted by Itar-Tass agency.

Foreign Minister Adnan Mansour said Tuesday he is taking his time to hand a letter of complaint to the Syrian envoy over Syria’s violation of Lebanon’s border because he is trying to first verify “some facts on the ground.”

On Monday, President Michel Suleiman condemned a recent infiltration by Syrian troops into Lebanon’s eastern border region of al-Qaa and the shelling of several border towns, asking Mansour to hand Syrian Ambassador Ali Abdul Karim Ali a letter of complaint.