Ban Ki-moon warns Syria 'world is watching'

Fresh clashes have erupted in Syria as a vanguard of UN monitors prepares to arrive to oversee the shaky ceasefire.

Activists said there was heavy shelling in the city of Homs, while Syrian state media claim that attacks by "terrorists groups" have intensified.

Speaking in Brussels, UN Secretary General Ban Ki-moon said he was "very concerned" at the developments, and "urged" Syrian forces to observe the ceasefire.