YANGON, Myanmar (AP) -- Another powerful storm headed toward Myanmar's cyclone-devastated delta today, and the U.N. warned inadequate relief efforts could lead to a second wave of deaths among the estimated 2 million survivors.

The country's junta told visiting Thai Prime Minister Samak Sundaravej, however, that it is in control of the relief operations and doesn't need foreign experts.

Samak visited a government relief center in Yangon and told reporters after returning to Bangkok the junta has given him the "guarantee" there are no disease outbreaks and no starvation among the cyclone survivors.

"They have their own team to cope with the situation," Samak said, citing Myanmar Prime Minister Lt. Gen. Thein Sein. "From what I have seen, I am impressed with their management."

International agencies say bottlenecks, poor logistics, limited infrastructure and the military government's refusal to allow foreign aid workers have left most of the delta's survivors living in miserable conditions without food or clean water. The government's efforts have been criticized as woefully slow.

The U.S. military's Joint Typhoon Warning Center said there is a good chance "a significant tropical cyclone" will form within the next 24 hours and head across the Irrawaddy delta area.

The area was pulverized by Cyclone Nargis on May 3, leaving at least 34,273 dead and 27,838 missing, according to the government. The U.N. says the death toll could exceed 100,000. An estimated 2 million survivors of the storm are still in need of emergency aid. But U.N. agencies and other groups have been able to reach only 270,000 people so far.

Dr. Thawat Sutharacha of Thailand's Public Health Ministry said today the junta has given permission to a Thai medical team to go to the cyclone-hit delta.

If the team is able to go as scheduled Friday, it would be the first foreign aid group to work in the ravaged Irrawaddy delta.

The junta has said it will allow 160 relief workers from neighboring countries to come to Myanmar, but it is not clear if they include the Thai medics or whether they will be allowed to travel to the delta.

"The government has a responsibility to assist their people in the event of a natural disaster," said Amanda Pitt, a spokeswoman for the U.N. Office for Humanitarian Affairs.

"We are here to do what we can and facilitate their efforts and scale up their response. It is clearly inadequate and we do not want to see a second wave of death as a result of that not being scaled up," she said.

The news of a second cyclone was not broadcast by Myanmar's state-controlled media. But Yangon residents picked up the news on foreign broadcasts and on the Internet.

"I prayed to the Lord Buddha, 'Please save us from another cyclone. Not just me but all of Myanmar,' " said Min Min, a rickshaw driver, whose house was destroyed in Cyclone Nargis. Min Min, his wife and three children now live on their wrecked premises under plastic sheets.

"Another cyclone will be a disaster because our relief center is already overcrowded. I am very worried," said Tun Zaw, 68, another Yangon resident who is living in a government relief center.

Prof. Johnny Chan, a tropical cyclone expert with City University of Hong Kong, said the new cyclone would likely not be as severe as Nargis because it is already close to land, and cyclones need to be over sea to gain full strength.

"There will be a lot of rain but the winds will not be as strong," he told the Associated Press.

Getting to the worst-affected areas was getting more and more difficult, and the impending storm was expected to compound the misery of the survivors.

"They are already weak," said Pitt, the U.N. spokeswoman. A new storm will affect "people's ability to survive and cope with what happened to them ... this is terrible."

Soldiers have barred foreign aid workers from reaching cyclone survivors in the hardest-hit areas, but gave access to an International Red Cross representative who returned to Yangon on Tuesday.

Bridget Gardner, the agency's country head, described tremendous devastation but also selflessness, as survivors joined in the rescue efforts.

"People who have come here having lost their homes in rural areas have volunteered to work as first aiders. They are humanitarian heroes," Gardner said.