UN-Arab League envoy to Syria Kofi Annan has quit his post, the UN Secretary-General Ban Ki-Moon says.
Mr Ban announced “with deep regret” the resignation of Mr Annan, who was named to the post on February 23.
Mr Annan’s resignation, which is effective as of August 31, as the civil war in Syria spirals further out of control.
Syrian rebels have bombarded a military air base in the northern city of Aleppo using a tank captured from government troops.
And a rights watchdog reported dozens of people were killed in a raid near the capital Damascus.
The Aleppo report was one of the first indications the rebels are starting to deploy the heavy weapons they have managed to capture in the past weeks from the Syrian army.
The Syrian Observatory for Human Rights said the rebel-seized tank shelled the Menagh military airport outside Aleppo, which the regime has used to launch attacks on rebel positions in the surrounding area.
Later, a nearby village was shelled by government forces out of that same airbase.
The report, however, represents an escalation in the battles between the two sides.
Up to this point, rebel forces have suffered because of a huge disparity in armaments with Syria’s well-armed military.
The United Nations earlier confirmed that rebels battling president Bashar al Assad’s regime now have heavy armour.
But the Syrian army still has many more tanks and armoured vehicles than the rebels and there was no indication that Thursday’s attack on the airbase was particularly effective.
