Ban said Assad had conveyed to him in a telephonic conversation that military operations against protesters had stopped and that the UN humanitarian assistance assessment team would be able to visit different places in the country.
"This is what he clearly told me when I had the telephone talk with him...It is troubling that he has not kept his word," Ban told reporters here.
The UN chief said world leaders have urged Assad to "immediately halt military operations that are killing his own people, and he assured me (he would) do that."
Ban said he "sincerely" hoped Assad would pay heed to calls by the international community to bring an end to the months-long violence in his country.
Meanwhile, the United Nations Human Rights Council met for a "special session" today to discuss sending another commission to Syria to investigate possible crimes against humanity in the government’s crackdown on protesters.
UN High Commissioner for Human Rights Navi Pillay presented to the Council in Geneva findings of a mission to Syria by her office covering the period from March 15 to July 15.
The draft resolution, which the Council is debating, calls on the Syrian authorities to fully cooperate with a new "independent international commission of inquiry" into alleged violations of international law.
The commission, to be appointed by the Council, would cover the period from July and report back by November end.
It would call on the Syrian government to immediately halt "all human rights violations," including "the continued indiscriminate attacks" on its people.
Pillay said more than 2,200 people have been killed since mass protests began in mid-March, with more than 350 people reportedly killed in Syria since the start of the Muslim holy month of Ramadan.
