United Nations:
UN monitors arriving in Syria are starting a perilous mission as there is no formal ceasefire between President Bashar al-Assad and opposition forces, diplomats said.
"No ceasefire, not even the start of a political process, this will be one of the most difficult UN missions ever," said one senior envoy at the United Nations.
The Syrian government is responsible for the safety of the 30 unarmed monitors who will be deployed in coming days, a UN Security Council resolution which approved the force stressed.
But with new attacks reported as the council voted on Saturday, Western nations have expressed widespread doubts that Assad plans to keep to the cessation of hostilities that started on Thursday.
The UN often sends military observers into trouble zones, they are widely known in missions around the world as the UNMOs (UN military observers) -- "the eyes and ears of the Security Council."
But the observers who went between Pakistani and Indian forces in 1948, separated Turkish and Greek-Cypriot fighters in Cyprus in 1974 and Maoist rebels and government forces Nepal in 2006 followed by the signing of ceasefire agreements.
About six of the advanced teams of 30 observers were to arrive on Sunday in Damascus. UN-Arab League special envoy Kofi Annan wants more than 250 in all but they can only leave if the fragile truce holds.
The first group got a plane from New York straight after Security Council resolution was passed.
The next 25 will come from missions around the Middle East and Africa "so we can move people quickly and they are experienced in the region," UN peacekeeping department spokesman Kieran Dwyer told Agence France Presse (AFP).
After setting up an operating headquarter in Damascus "they will quickly reach out to contacts both within the Syrian government, and their security forces, and with the opposition forces so that all sides fully understand their monitoring role," said Dwyer.
"They will visit other cities quickly to establish where they need to set up bases as the team is built up and also to reach out to have contacts in the other cities."
The advanced team will have to establish a routine "moving about and liaising on a day-to-day basis and monitoring that the violence has actually stopped," the spokesman added.
The observers will report to Mr Annan and the UN headquarters in New York so that the Security Council can decide on the next steps in the mission.
The monitoring mission is just one part of the six-point peace plan that the Syrian President agreed with Mr Annan.
"Joint Special Envoy Mr Annan will continue to work on the other parts of the six-point plan," said Dwyer.
"The monitors are not going to do any political work and people must not have overly ambitious expectations of what monitors can do," said the UN spokesman.
"As the security council has said, and Secretary General Ban Ki-moon has said: It is the responsibility of the Syrian government and opposition to cease all forms of violence and ensure that this cessation holds," Dwyer stated.
The shelling of rebel districts in Homs and firing on funeral mourners in Aleppo on Saturday reinforced the dangers of the mission.
"This resumed violence casts serious doubts yet again on the regime's commitment to a cessation of violence," US ambassador Susan Rice told the UN Security Council after the vote allowing the advance party.