Mr Ban was told of the refusal when he held a second round of talks with military leader Gen Than Shwe.
"I'm deeply disappointed," he told reporters. "I'm very sorry to report to you that this is not possible."

Mr Ban said he had been assured that elections planned for 2010 would be "held in a fair, free and transparent manner".
The UN chief is due to make a speech outlining his vision for Burma later on Saturday.