Story highlights Six monitors will begin work Monday, spokesman says; 24 more are expected soon

At least 23 people die across Syria in violence Sunday, opposition activists say

Syria must coordinate "all the steps on the ground" for U.N. observers, a government spokeswoman says

An advance team of 30 members is expected to pave the way for a larger group of 250 observers

The first members of a U.N. monitoring team have arrived in Syria, a U.N. spokesman said early Monday, four days after a so-called cease-fire that is showing serious signs of collapse.

The six monitors arrived Sunday in Damascus and will begin their work Monday morning, said Kieran Dwyer, a spokesman for peacekeeping missions at the United Nations.

"They will be liaising with the Syrian government, security forces and the opposition members to establish the monitoring process across the country," Dwyer said.

The first members of the advance team arrived a day after the U.N. Security Council voted unanimously to authorize unarmed observers to travel to Syria to monitor the shaky cease-fire.

The 15-member council approved the deployment of an advance team of 30 monitors meant to pave the way for a larger group of up to 250 observers, calling on Syria to provide them unimpeded freedom of movement. The remaining 24 members of the advance team will arrive in Damascus in the coming days, Dwyer said.

The second, larger deployment rests on how the cease-fire holds and whether discussions between Syria and U.N.-Arab League envoy Kofi Annan can make headway to quell the bloodshed.

Still, the resolution marks the Security Council's first on Syria since the conflict gripping the country broke out more than a year ago.

U.N. Secretary-General Ban Ki-moon pledged to try to develop by Wednesday a more concrete proposal for an official, and likely more broadly defined, observer mission.

Bouthaina Shaaban, a Syrian government spokeswoman and presidential adviser, said Sunday that the "length of work of the observers and their movement will be determined in coordination with the government of Syria." A protocol agreement on the observers' mission will need to be signed before the larger group is allowed to come, she said, according to a transcript on the website of state-run Al Dunya TV.

"Syria cannot be responsible for their security unless it participates and coordinates all the steps on the ground," she said.

U.N. team members arrived amid reports of ongoing bloodshed, as government helicopters pounded the besieged city of Homs from the sky, opposition activists said Sunday.

In addition, "one bomb is being shelled every 10 minutes from the military academy, aiming at al-Wair neighborhood in Homs," said the Local Coordination Committees of Syria, a network of opposition activists.

At least 23 people died across Syria on Sunday, including 11 in Homs, the LCC said.

The state-run Syrian Arab News Agency blamed "armed terrorists" for violating the cease-fire, quoting an unnamed military official's assessment that the groups "have hysterically escalated their aggressions on the army, the law enforcement forces and the civilians."

The Syrian regime has consistently blamed the violence in the country on such groups, but many world leaders have said the government is lethally cracking down on dissidents seeking democracy and an ouster of President Bashar al-Assad, whose family has ruled Syria for 42 years.

CNN cannot independently verify reports of violence and deaths as the government has severely restricted access by international media.

Though critics called the Security Council's resolution underwhelming, the U.N. ambassador from Russia -- whose country has previously blocked the council's resolutions -- reminded those strident for action in Syria that the text requires all sides to put down their weapons.

"There have been too many casualties, too much suffering to befall the Syrian people," Ambassador Vitaly Churkin said Saturday.

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He also said that his government has been discouraged by a lack of objective information and has called on Syria to allow in international journalists.

Until Saturday, Russia and China -- which both have major trade ties with Syria -- had blocked Security Council attempts to pass resolutions condemning the al-Assad government. While the two countries have said they want an end to the violence, both have argued that previous resolutions were not even-handed.

U.S. Ambassador to the U.N. Susan Rice welcomed Saturday's long-awaited resolution, but said the United States was "under no illusions" about its immediate effect.

Rice, the current Security Council president, pointed to reports of ongoing violence, which are already "raising renewed doubts about the sincerity" of Syrian authorities to end hostilities.

Renewed shelling on Homs on Saturday "absolutely" constituted a violation of the current cease-fire, she said.

While the council's decision "does not satisfy us fully," Syria "will be on board" with the resolution, Syria's U.N. ambassador Bashar Jaafari said.

Jaafari also called for a lifting of sanctions, blaming them for costing his country "billions of dollars."

Earlier, Ambassador Mark Lyall Grant of the United Kingdom warned that a narrow window now exists to improve conditions on the ground.

The U.K., he said, welcomes the resolution, but regrets "that it comes only after the Syrian people have for over one year suffered unimaginable brutality at the hands of a regime that has prioritized its own survival over the needs, rights and aspirations of the people it should serve and protect."

Separately, Iran's chief nuclear negotiator Saeed Jalili told reporters in Turkey that the Syrian issue "has only one solution, and that is democracy."

The United Nations estimates at least 9,000 people have died since the protests began, while others put the death toll at more than 11,000.