Activists say Syrian troops are heavily shelling rebel-held areas in the central city of Homs, just one day after the U.N. General Assembly condemned the regime for violating human rights in its crackdown.

The activists said tank fire and artillery shelling hit four neighborhoods in the central protest city Friday which has spearheaded the 11-month uprising against President Bashar al-Assad.

On Thursday, U.N. Secretary-General Ban Ki-moon accused the Assad government of "almost certain" crimes against humanity.