UN Chief Ban Ki-moon met with Myanmar Prime Minister Thein Sein on Thursday, in a high-profile diplomatic push to press the junta to accept a full-scale relief operation for cyclone survivors.

The meeting was for about 20 minutes at the Sedona Hotel in Myanmar's main city of Yangon, AFP reported.

Ban Ki-moon arrived in Myanmar earlier this morning to convince the regime to welcome a major international relief operation three weeks after the cyclone disaster.

With around two million desperate survivors still facing dire shortages of food, water, shelter and medicine, the junta's isolationist leader Than Shwe has stunned the world with his refusal to accept a major aid effort.

Ban was to meet with Than Shwe on Friday in the regime's remote capital of Naypyidaw. Ban repeatedly failed to get the general to take his phone calls after the May 2-3 storm, which left at least 133,000 people dead or missing.

“Our focus is on saving lives,” he said in Bangkok on the eve of his trip, aimed at winning a bigger role for the international community in the relief effort.

The UN Secretary General began his official programme by making an offering for the storm's victims at the Shwedagon Pagoda, the holiest Buddhist shrine in Myanmar.

It is the first visit to Myanmar by a UN Secretary General since 1964. The last trip was by U Thant, a Myanmar national, who led the world body when this country was still known as Burma.

The United Nations estimates that only 25 per cent of those in need have been reached by international aid.

Although the United Nations has been critical of Myanmar's human rights record, Ban has insisted the aid effort should not be politicised.

The impoverished nation has accepted tonnes of donations from around the world, and has allowed US military planes to airlift supplies into the Yangon airport.

The regime this week also agreed to allow nine UN helicopters to work in remote regions hit by the storm, but still refuses to allow five US and French ships laden with relief supplies to enter the country.

Scores of medics from around Asia have been allowed to begin treating victims of the tragedy, but Myanmar has refused to issue visas to most disaster relief specialists, whose skills are needed to run a complex aid operation.

Ban said that he wanted a logistics hub inside Myanmar, which has agreed to a joint mechanism between the United Nations and the Association of Southeast Asian Nations (ASEAN) to coordinate the emergency effort.

Exactly how that mechanism would work remains unclear, but the United Nations and ASEAN are set to host a donor meeting on Sunday in Yangon to raise money for the operation.

Despite the tragedy and the intense diplomatic manoeuvring, Myanmar's junta is pressing ahead with its own political agenda.

Just days after the storm, the regime held a first round of voting on a new constitution, which dissidents say will entrench military rule.

The regime now insists on holding a second round of voting in the referendum on Saturday in towns and villages that were devastated by the cyclone.

The regime's main foe, Nobel peace prize winner Aung San Suu Kyi, is under house arrest, and her detention is expected to be extended by Monday.

Aung San Suu Kyi led her National League for Democracy to a landslide victory in Myanmar's last national elections in 1990, but the regime has never recognised the result and instead has kept her locked up for more than a decade.