Thousands demonstrated in support of the rebel Free Syrian Army on Friday, as activists said security forces shot dead 13 people in several regions and longtime Damascus ally Moscow kept up its opposition to calls for tougher action against the regime.

The Local Coordination Committees, the main activist group spurring protests on the ground, said regime troops shot dead two people in the northern province of Aleppo, one in the central province of Hama, one in the eastern oil hub of Deir al-Zour, five in the central opposition bastion Homs, one in the southern province of Daraa and two in the Damascus suburb of al-Damir.

France on Friday opened a murder probe into the killing of a French journalist in Syria, amid suspicions of regime collusion in the first death of a Western journalist since protests began 10 months ago.

Judicial sources said a murder enquiry had been opened into the killing on Wednesday of 43-year-old France 2 television reporter Gilles Jacquier during a government-organized trip to Homs, a flashpoint for anti-regime protests.

A Russian ship, allegedly carrying tons of weapons, made a dash for Syria after Cypriot officials allowed it to leave their waters, Turkish officials said Thursday.

The ship had made an unscheduled stop in Cyprus Tuesday, technically violating an EU embargo on arms shipments to Syria, which has killed thousands in a crackdown on dissent.

British Prime Minister David Cameron held talks with Saudi King Abdullah bin Abdul Aziz al-Saud in Riyadh on Friday, as tensions soar between the West and Tehran, the oil-rich kingdom's arch-rival in the Gulf.

The two leaders "discussed the importance of the UK-Saudi bilateral relationship and agreed to strengthen cooperation in a range of areas," Cameron's office said in a statement.

Russia said on Friday it strongly disagreed with changes to its draft U.N. Security Council resolution on Syria that are being promoted by Western states.

"Unfortunately, the West's approach radically differs from ours," Deputy Foreign Minister Gannady Gatilov was quoted as saying by Interfax.

Syria said on Thursday it would set up a commission of inquiry into the death of French journalist Gilles Jacquier, killed by a shell in the flashpoint city of Homs on Wednesday, official media said.

"The governor of Homs, Ghassan Abdul Al, issued a decision to create a commission charged with investigating the circumstances of the terrorist attack that cost the life of the French journalist and eight Syrians," the official SANA news agency said.

Authorities prevented a convoy of 200 opposition activists Thursday from entering Syria via Turkey with medical aid for victims of the ongoing uprising, an Agence France Presse reporter at the border said.

Some of the activists said they had traveled from as far afield as the United States and western Europe in order to join the so-called Freedom Convoy which included five buses and several cars.

France said on Thursday it respected the decision of some Arab League observers to resign from the Syria monitoring mission but said it remained crucial to ending repression.

Arab League officials confirmed that two monitors had quit the mission, including an Algerian who accused the Syrian regime of duping his colleagues.

The opposition Syrian National Council accused the regime on Thursday of "liquidating" journalists in order to hush up what is happening in the country, a day after a French reporter was killed.

The SNC's accusation came as France demanded an investigation into the death the previous day of Gilles Jacquier, 43, who worked for France 2 television, during a government-organized trip to the flashpoint city of Homs.

China's envoy to the Middle East Wu Sike on Thursday said Arab League observers were facing "difficulties" in Syria, urging the government and other factions there to cooperate with the monitors.

Wu made the remarks after talks with Arab League chief Nabil al-Arabi at the bloc's Cairo headquarters, days after three monitors were slightly hurt in the Syrian coastal city of Latakia.