|A piece of a Syrian military shell is shown during the bombardment on al-Khaldiyeh on Monday [SHAMSNN/YouTube]
The Syrian army has shelled a district in the flashpoint city of Homs, killing at least five people as the troubled opposition continues to try to unite its various factions.
Al-Khaldiyeh, targeted in a week-long campaign to flush out anti-government forces, was hit by mortar rounds on Monday that set alight houses in the neighbourhood, said the Local Co-ordination Committees (LCC), an activist network.
"The regime is trying to storm the neighbourhood," the LCC group said in a statement.
The shelling killed five people, according to the Syrian Observatory for Human Rights, a monitoring group based in the United Kingdom.
The assault came as Syrian opposition factions gathered in Istanbul in a bid to unify ahead of an international meeting to be held in Turkey on Sunday.
"We will have a welcoming reception tonight and will hold meetings all day Tuesday," Mohamed Sermini, a member of the main opposition Syrian National Council, told the AFP news agency. "The aim is for the opposition to agree on a united position and to outline the major points of a national pact."
The crisis in Syria is expected to dominate a three-day summit of the Arab League beginning in Baghdad on Tuesday, and the so-called "Friends of Syria" - a coalition dominated by European and Gulf countries and the United States - will meet on Sunday in Istanbul.
Violence raged elsewhere in Syria on Monday, from the northwest near the Turkish border to Deir al-Zor in the east.
Sniper fire reportedly killed one person in the northwestern province of Idlib, and an 18-year-old woman died in clashes in Harasta, a Damascus suburb.
In Idlib, clashes between opposition fighters and government forces were reported in various towns including Darkush and Kfar Nabl, where arrests were taking place, the Observatory said.
The state news agency SANA said the clashes in Darkush took place after regime forces managed to thwart an attempt by "terrorists" to enter the restive province from Turkey.
Clashes were also reported in Deir al-Zor, where security forces carried out dawn raids in which 16 people were arrested, the Observatory said.
The Observatory said that in al-Hassake province, in the northeast, the body of Khalaf Mohamed Qatana, nephew of the slain Kurdish leader Mishaal Tammo, was discovered on Monday, a day after he was kidnapped.
The UN says that more than 8,500 people have been killed since the uprising broke out in mid-March last year.
After the Syrian military subdued the rebel district of Bab Amr in Homs in March, clashes have shifted north towards the border with Turkey.
President Bashar al-Assad's government has sought to drive rebels from Idlib and Aza, while Turkey has suggested it may create a "buffer zone" inside Syria to push humanitarian assistance.
Perhaps in preparation for such a move, Turkey suspended all activities at its embassy in Damascus, the foreign ministry said.
A Turkish diplomatic source on Monday said the mission was closed because of deteriorating security conditions in Syria and that all diplomatic personnel had left Damascus.
The source added that the consulate in the northern city of Aleppo would remain open. Norway also announced on Monday that it had closed its embassy.
Turkey is providing sanctuary to more than 16,000 Syrians who have fled the violence, including defected soldiers and generals. Prime Minister Recep Tayyip Erdogan has called on all Turkish citizens in Syria to return home.
On Sunday, Dmitry Medvedev, the Russian president, warned Syria that Kofi Annan represented the last chance for avoiding a civil war and offered the UN-Arab League envoy Moscow's full support.
Annan was expected to head to China on Monday after asking Russia to back his mission to end fighting in Syria.
Both Russia and China have used their veto rights as permanent members of the UN Security Council to block efforts to condemn Assad and begin a transition that would see him leave power.
Annan's mission calls for Assad to withdraw troops and heavy weapons from protest hubs, a daily two-hour humanitarian ceasefire, access to all areas affected by the fighting and a UN-supervised halt to all clashes.
The Syrian National Council has slammed Annan's mission as a waste of time unless military pressure is brought to bear against Assad's forces. But the United States and Europe have both stated strong opposition to arming the rebels, much less intervening with their own forces.