UN chief Ban Ki-moon has accused Iran, Qatar and Saudi Arabia of arming the Syrian conflict, spreading misery as the fighting intensifies.
The latest unverified video said to be in Aleppo certainly illustrates the use of heavy weaponry.
Meanwhile the new UN and Arab League envoy for Syria Lakhdar Brahimi called for unity in addressing the crisis during his first speech to the General Assembly.
“I am looking forward to my visit to Damascus in a few days time and also, when convenient and possible, to all countries who are in a position to help the Syrian-led political process become a reality leading to a transition that respects the legitimate aspirations of the Syrian people.”
On Tuesday the Syrian president promised the Red Cross he would allow the organisation to expand its relief operations.
As reports grow of a worsening humanitarian crisis in several bombarded cities, a video taken off the internet purported to show the discovery of 18 bodies dumped at a hospital in Douma.