Two members of the advance team remained in the central city of Homs on Sunday, a mission spokesman said.

This video uploaded to YouTube showed four of the UN observer meeting with activists who begged them to stay in Homs. 

"Today is the first day since two months, exactly since 5 February... in Homs without shelling... without killing, without fire," one activist said in the footage.

"Because of that, we want you to stay. Please stay. This is what we want. When you come, shelling stops. When you come, killing stops," he told the observers, who wore blue helmets and bullet-proof vests marked "UN".