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.

Palestinian militants in the Gaza Strip fired a rocket toward the southern Israeli city of Ashkelon on Tuesday evening but it was intercepted by the Iron Dome air defense system, the military told Agence France Presse.

On Friday two rockets slammed into open ground in Israel's south, without causing casualties or damage.

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.

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.

The United States is stepping up support for the Syrian opposition amid signs events in the 16-month uprising are moving faster on the ground, Secretary of State Hillary Clinton said Tuesday.

After failing to win a U.N. Security Council resolution on Syria after Russia and China imposed their vetoes, the United States is working outside the council to send "a clear message of support for the opposition," she said.

Russia urged its Middle East ally Syria on Tuesday to refrain from using chemical weapons despite its threat to unleash the previously unreported arsenal in case of a foreign attack.

The foreign ministry said it "would like to underline that Syria joined" a Geneva protocol on the non-use of such weapons and "presumes that the Syrian authorities will continue to rigorously abide by its assumed international obligations".

More than 10,000 Iraqis have fled Syria to return home since Wednesday fearing for their lives, the U.N. refugee agency said.

"Many of the returnees have expressed their fear regarding the ongoing risks to their safety in Iraq, but said they had little choice, given the security threats in Syria," UNHCR spokeswoman Melissa Fleming said in Geneva on Tuesday.

Renowned Syrian sculptor Wael Qastoun has been tortured to death in the flashpoint central of city of Homs, an artists' association said on Tuesday.

A statement released by the Syrian Coalition of Artists for Freedom said Qastoun "died under torture."

Syrian government troops attacked the Qadam and Assali districts of Damascus on Tuesday, two of the last pockets of rebel-held territory in the city, a watchdog said.

"Syrian regime forces have attacked the Qadam and Assali districts, launching a wave of raids and arrests," the Britain-based Syrian Observatory for Human Rights said.

Syrian rebel forces are stretching the Syria army nationwide, grabbing border posts and countryside regions as they challenge the regime in its symbolic power centers of Damascus and Aleppo, experts say.

An attack in the heart of Damascus last week, claimed by the rebel Free Syrian Army, killed four senior regime members and forced the government to redeploy troops to the capital, leaving gaps elsewhere that the rebels can exploit.