Whenever US-backed mercenaries suffer a heavy blow in Syria, Washington resorts to the recurring and fabricated allegation of chemical attacks by Damascus, Iranian official Ali Akbar Velayati said.

Velayati -an international adviser to the Leader of the Islamic Revolution- slammed the US allegation that the Syrian government has launched chemical attacks, describing it as "a repeated, fabricated propaganda trick that follows the defeat of US-backed militants in Syria," Tasnim News Agency reported.

Velayati also reaffirmed Iran’s commitment to supporting the Syrian nation and its legitimate government, and to strengthening the axis of resistance, including Iran, Iraq, Syria and Lebanon.