United Nations experts will accompany a Syrian government-led humanitarian mission, the second time UN personnel have visited protest sites this month, the organisation's humanitarian chief has said.
Valerie Amos said on Thursday that UN technical experts would join the Syrian mission, but she demanded the observers be given free access to to restive cities.
Analysts said the delegation, which will visit Homs, Deraa and Hama, where thousands have been killed, fell short of an earlier offer of a joint assessment mission. It is not scheduled to visit Idlib, in the north, the most recent site of major clashes between the army and armed opposition.
Amos said the mission would start this weekend and also visit Tartous, Latakia, Aleppo, Deir al-Zour and rural areas around Damascus.
She said technical staff from the UN and Organisation of Islamic Cooperation would join the mission "and take the opportunity to gather information on the overall humanitarian situation and observe first-hand the conditions in various towns and cities".
But Amos stressed that "it is increasingly vital that humanitarian organisations have unhindered access to identify urgent needs and provide emergency care and basic supplies".
In a message to mark the first anniversary of the start of protests in Syria, UN Secretary-General Ban Ki-moon said President Bashar al-Assad had "responded with brutal repression, which has continued unabated". He said "well over" 8,000 people have died.
"It is urgent to break the cycle of violence, stop military operations against civilians and prevent a further militarisation of the conflict in Syria," Ban said.
He expressed "solidarity" with the Syrian people and called on the Syrian government and opposition to co-operate with Kofi Annan, the joint UN-Arab League special envoy, who has tried to start negotiations between Assad and the opposition. Annan is set to brief the UN Security Council on his efforts on Friday.
As the opposition marked the first anniversary of the revolt on Thursday, government troops pressed ahead with their efforts to control key cities in the south and north.
In Idlib in the north, soldiers have driven out rebel forces and many civilians, and in Deraa, the site of the country's first major anti-government protests in March 2011, soldiers supported by armoured vehicles have launched renewed attacks.
Assad supporters marked the occasion with rallies across the country, including in the capital Damascus, saying the uprising was a "conspiracy" against the state.
Pro-Assad rallies were also held in Suweida to the south and al-Hassake in the northeast.
"After a whole year of pressure on Syria, we want to make the world hear our voice: Leave Syria in peace," a woman on the street told a government television station.
The most prominent opposition bloc, the Syrian National Council, has said it wants to arm civilians and defected soldiers fighting the vastly better-provisioned army, but most nations who oppose Assad's crackdown also fear intervening militarily.
France's foreign minister, Alain Juppe, said on Thursday that arming the opposition risked pushing the country into a catastrophic civil war.
"The Syrian people are deeply divided, and if we give arms to a certain faction of the Syrian opposition, we would make a civil war among Christians, Alawites, Sunnis and Shias,'' Juppe said on France-Culture radio.
The government's military offensive has forced thousands of Syrians to flee the country, most of them to neighbouring Lebanon and Turkey. The UN's refugee agency says that about 230,000 Syrians have fled their homes, of whom almost 30,000 have left the country.
Turkey is hosting more than 14,000 Syrian refugees, including seven defected generals, a foreign ministry spokesman said on Thursday. Roughly 1,000 Syrians had arrived in the past 24 hours, he said.