Syria: United Nations observers arrive in Damascus as cease-fire wavers (VIDEO)

BEIRUT, Lebanon — Six United Nations observers arrived in Syria overnight, the first batch of a force intended to monitor Syria's compliance with a cease-fire and six-point peace plan, which the Associated Press called "rapidly unraveling."

The news wire said activists reported a resumption of shelling and mortar fire in the rebellious city of Homs, apparently breaching the cease plan, which called for a cessation of hostilities by both sides.

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The number of observers is expected to eventually grow to 250; 25 additional monitors will arrive "within days," The New York Times wrote. 

Ahmad Fawzi, spokesman for joint United Nations-Arab League envoy to Syria Kofi Annan, told the Times that the diplomats “will start with setting up operating headquarters and reaching out to the Syrian government and the opposition forces so that both sides fully understand” their role.

UN Secretary General Ban Ki Moon said he hoped the arrival of the full inspection team will be met with "calm and stability and peace without any violence," the AP said.

The cease-fire has brought reduced violence; widespread shelling has stopped "with the exception of Homs," and government troops are ignoring a peace plan requirement to pull out of population centers. "Rebel fighters have also kept up attacks, including shooting ambushes."

Below is a video purportedly showing the Homs neighborhood of Qarabis, which activists say was shelled last week.