former U.N. Secretary General Kofi Annan (Photo: AP)
UN-Arab League envoy Kofi Annan called for the rapid deployment of 300 ceasefire monitors in Syria but a top UN official said it will take at least one month to get the first 100 in place.
UN Security Council powers called on the United Nations to speed up the deployment.
Annan said Syrian President Bashar al-Assad has still not fulfilled a promise to end violence and said the situation was "bleak" and "unacceptable".
The special envoy said he was "particularly alarmed" at reports that government forces had entered the city of Hama after a visit by UN monitors and killed "a significant" number of people.
"If confirmed this is totally unacceptable and reprehensible," he told the council.
The Syrian League for Human Rights said nine activists were "summarily executed" by government forces in Hama on Monday, a day after they met UN observers in the city.
Video footage posted online by activists showed a street in Hama's Arbaeen neighborhood with large pools of blood and women weeping.
The council was told there are now 11 UN observers in place and the 30-strong advance party of the UN Supervision Mission in Syria (UNSMIS) is expected to be in place by the end of the week.
But UN peacekeeping chief Herve Ladsous said it would take a month to get the first 100 of the 300-member full force into Syria.
"All council members underscored the need for more rapid deployment of observers," US ambassador Susan Rice told reporters.
"We simply urged them to maybe look for some unorthodox ways to maybe expedite the process," Russia's UN envoy Vitaly Churkin said.
Damascus is however refusing to accept monitors from the Western and Arab coalition of countries in the so-called Friends of Syria group which has backed the opponents of Assad, Ladsous told the council.
The Syrian government had also blocked at least one observer because of his nationality, the official added.
"He underscored that from the UN's point of view this was entirely unacceptable," Rice said.
The United States, France, Britain, Germany, and Arab nations Saudi Arabia and Qatar are leading members of the Friends group which Damascus has dubbed the "Enemies of Syria" group.
The Security Council voted on Saturday to send the full UNSMIS force, only days after UN Secretary General Ban Ki-moon called for 300 monitors.
"We must ensure that the momentum generated by the council's speedy decision is not lost," Annan said. "The expeditious deployment of UNSMIS," he added, "is crucial."
"We need eyes and ears on the ground, able to move freely and quickly, and to engage all parties -- something which must be guaranteed by the Syrian authorities."
"Sustained pressure and engagement from the international community is essential," Annan said.
The Syrian government wrote to Annan on Saturday saying that troops and heavy weapons had been withdrawn from cities in line with promises made to the envoy.
But Annan's spokesman, Ahmad Fawzi, said earlier that satellite imagery had since shown that the government has not yet removed heavy weapons.
Annan brokered a cessation of hostilities which started on April 12, but the killing has continued, strengthening the doubts of Western nations that Assad will halt his crackdown on a 13-month-old uprising. The UN says well over 9,000 people have been killed.
Ladsous said Ban would name the monitoring mission's chief by the end of the week.
Major General Robert Mood of Norway, who negotiated the deployment with the Syrian government, attended the Security Council meeting and is considered the favorite to lead the mission.