Cyclone survivors take shelter at a temple on the outskirts of Rangoon on Tuesday. (Associated Press)

Shipments of food, medicine and supplies are piling up at Burma's international airport in Rangoon, but they aren't making it into the hands of the cyclone victims who need it most, the UN said Tuesday.

The UN estimates its World Food Program is only getting 20 per cent of the food needed into the country and to victims who are facing starvation.

Poor infrastructure and pounding rain are being blamed, but foreign agencies are also pointing fingers at Burma's ruling military junta, which has banned some international aid planes from entering the country and has refused to provide visas for many foreign aid workers.

Rumours are swirling that the junta is hoarding the best foreign aid supplies for itself.

"There is obviously still a lot of frustration that this aid effort hasn't picked up pace," said Richard Horsey, a spokesman for the UN humanitarian effort operating out of Bangkok.

Death toll could pass 100,000: UN

Cyclone Nargis ravaged Burma, also known as Myanmar, on May 3, leaving an estimated 62,000 people dead or missing, according to the official state count. But the UN fears the death toll is well beyond 100,000.

An estimated two million survivors have seen their homes and rice farms washed away, and are now struggling to find shelter, food and medicine. Many are at risk of disease.

"We are not reaching people quickly enough," Horsey said in an interview with the Associated Press.

A handful of planes from the U.S., Red Cross, UN and other agencies have made it into Burma with supplies, and the junta has assured the U.S. military that humanitarian workers in the country are doling the aid out to those in need.

But residents and aid workers have told reporters that high-energy biscuits and good-quality rice is being kept by the military, while rotting rice and low-quality biscuits are being given to citizens.

"I have a small sample in my pocket and it's some of the poorest quality rice we've seen," said Brian Agland, director of Australia's branch of the charity CARE. "It's affected by salt water and it's very old."

"Certainly we are concerned that [poor quality rice] is being distributed. The level of nutrition is low."

Other aid workers complain of being forced to leave the hardest hit areas in the Irrawaddy Delta and return to the city of Rangoon. Armed police checkpoints are set up on roads leading into the delta, where police are taking down foreigners' names and passport numbers.

"We can go for two days, then we have to come back," said Jean-Sébastien Matte of Médecins Sans Frontières. "We're able to do 100 or 200 consultations a day, but we should be doing 1,000."

With files from the Associated Press