UN observers inspected the site of a deadly explosion that flattened a block of houses in the central Syrian city of Hama killing at least 16 people.
The government and the opposition traded blame for the blasts. Syrian state-run media said rebel bomb-makers accidentally set off the explosives, while anti-regime activists said intense shelling by government forces caused the extensive damage. It was impossible to independently verify the conflicting accounts because President Bashar Assad's regime, facing a 13-month-old uprising, has restricted access for journalists and other outside witnesses.
The spokesman for UN special envoy Kofi Annan, Ahmad Fawzi, said observers visited the site but there was no immediate word on what they saw. A pair of UN observers is stationed in Hama, part of an advance team of 15 that is to be expanded in the coming weeks to up to 300 as part of a truce plan to end the Syrian crisis.
A UN official said the United Nations has so far negotiated for countries to provide 100 unarmed truce monitors to be on the ground in Syria, in addition to civilian support staff, within 30 days of the April 12 cease-fire.
But he said differences between politicians and military officials in potential contributing nations have slowed the negotiations for more troops. He did not elaborate.
The official said the UN will announce Friday that Norwegian Major General Robert Mood is being appointed to lead the team of UN observers. He spoke on condition of anonymity because the announcement has not yet been made.
Amateur videos said to be of Wednesday's blasts in Hama showed a large cloud of white and yellow smoke rising from a neighbourhood surrounded by green fields. In a later video, dozens of people are searching the debris, including huge chunks of cement and broken cinderblocks. Another clip shows the bloodied body of a little girl being carried through a crowd of wailing men.
The state-run Syrian news agency SANA said rebels mishandling explosives triggered a blast that killed at least 16 people and severely damaged at least six houses.
The Local Coordination Committees, a network of activists, said the destruction was caused by intense shelling from government tanks, and denied that rebels were responsible for the blast.
Syrian activists claimed that 70 people died in the blast, many of whom were women and children.
A second group, the Britain-based Syrian Observatory for Human Rights, said the cause of the destruction was not immediately clear. The Observatory initially cited reports by local residents that they had come under attack from regime forces.
However, the head of the group, Rami Abdul-Rahman, said he cannot be sure those reports are accurate, and called for an investigation by UN observers.
With the violence in Syria continuing despite UN-led efforts to implement the ceasefire, the international community has grown increasingly impatient with the Assad regime.
French Foreign Minister Alain Juppe said that France had discussed invoking Chapter 7 of the UN Charter, which can be enforced militarily, with other world powers. US Secretary of State Hillary Clinton said last week the UN should move toward such a step to allow for measures like travel and financial sanctions and an arms embargo. She didn't mention military action. For more than a year, the US has opposed the further militarisation of the situation.
Any such move, however, would likely be blocked by Russia and China, which have twice used their vetoes as permanent Council members to protect Syria from condemnation and remain opposed to military intervention. Western powers, too, don't appear interested in sending forces to another Middle East nation in turmoil.
Russia's Foreign Ministry spokesman Alexander Lukashevich said Thursday that violations of the cease-fire were still being committed by both sides, but blamed the opposition.
"Most often this occurs because of provocative actions from the armed opposition, which often force the Syrian security forces to open fire in response," he said. Still, he added, the level of violence in the country has declined considerably since the observers arrived.
"All of this allows us to claim that the situation in Syria is starting to improve slightly, although this is a very fragile trend," he added.
Bassma Kodmani, a spokeswoman for the opposition Syrian National Council, called Thursday for a unified Arab stand against what she said was Damascus' failure to honour terms of Annan's peace plan. She said the Council wanted the Arab League to "open the door" to a UN Security Council resolution that would create safe havens in Syria and allow international relief agencies to operate there freely.
Kodmani spoke to reporters in Cairo ahead of a meeting of Arab foreign ministers scheduled for later Thursday in the Egyptian capital.
Kodmani said she told Arab League chief Nabil Elarabi that Arab foreign ministers must "rise above their differences" and send a strong message to the Syrian regime to immediately halt violence against civilians.
Arab countries are divided on their response to the Syrian crisis, with Gulf countries led by Qatar and Saudi Arabia in favor of arming the opposition and others like Egypt, Iraq and Sudan preferring a diplomatic solution.
For now, the international community remains united in support of Annan's plan, which calls for a cease-fire, to be followed by talks between the regime and the opposition on a political solution to the conflict that the UN says has killed more than 9,000 people.
That plan, however, has been troubled from the start. Syria has failed to enact key parts of the plan, like withdrawing its forces from cities, and its troops have attacked opposition areas, killing scores of civilians since the truce was to begin on April 12. Rebel fighters, too, have attacked military checkpoints and convoys.