Secretary-General Ban Ki-moon will fly to Burma this week and visit the areas hardest hit by Cyclone Nargis, a U.N. spokeswoman said Sunday.

Burma's military government has given permission for the U.N. chief to travel to the Irrawaddy delta, where U.N. officials fear tens of thousands of cyclone survivors are not getting adequate aid, U.N. spokeswoman Michele Montas said.

Ban sent U.N. humanitarian chief John Holmes to Burma, as called Burma over the weekend to assess the needs of the survivors and urge the isolationist junta to open its doors to more international aid.

The military junta has not allowed most international relief workers into the devastated region.

Burma's military leader, Senior General Than Shwe, has refused to take the secretary-general's phone calls or answer two letters sent urging that international relief teams be allowed in quickly to provide relief.

At least 78,000 people were killed in the May 2-3 storm and another 56,000 are missing.

Ban will leave New York on Tuesday and is scheduled to arrive in Burma's commercial capital, Rangoon, on Wednesday, Montas said.

"He will go to the areas most affected by the cyclone," she said.

The secretary-general will leave Burma on May 23 and stop in Bangkok, Thailand, on his way back to New York, she said.