The head of the United Nations arrived in South East Asia today, hoping to convince the Burmese generals who have snubbed his phone calls to accept a full-scale relief operation for the victims of Cyclone Nargis.

Before leaving New York, Ban Ki Moon announced that the Burmese junta had agreed to let nine UN helicopters work in remote regions hit hard by the storm, which has left at least 133,000 people dead or missing and two million more in dire need.

Mr Ban's humanitarian envoy, the Briton Sir John Holmes, announced separately that the UN chief would meet Than Shwe, Burma's "Senior General" on Friday in Naypidaw, the country's newly built capital.

Than Shwe, who took two weeks after the disaster to meet victims and see the destruction for himself, had declined to take Mr Ban’s phone calls after the storm hit on May 2. "That should be a very important meeting," Sir John told reporters in Bangkok after an inspection visit to Burma.

There has been an international uproar over the limits on the aid operation imposed by the isolated junta. The junta’s English-language mouthpiece, the New Light of Myanmar paper, said today that the regime would not take aid coming from US military ships and helicopters because of unspecified “strings attached".

The United States has repeatedly said that its aid is unconditional, and Mr Ban will try to get the generals to open up to more help to prevent more lives being lost. “This is a critical moment for Myanmar (Burma)," he said before his departure. "We have a functioning relief programme in place but so far we have been able to reach only about 25 per cent of Myanmar’s people in need. I am confident that emergency relief efforts can be scaled up quickly.” Mr Ban is to spend the night in neighbouring Thailand before flying into Burma tomorrow.

The UN said that up to 2.4 million people were struggling to survive in Rangoon and the Irrawaddy Delta, where refugees from the storm have been begging for food from relief workers. Ko Kyaw Khine, a Rangoon-based volunteer, said that the authorities in a village he visited on Tuesday used loudspeakers on trucks to tell people not to wait at the roadside because “begging from the donors tarnishes the dignity of the nation”.

The UN's World Food Programme (WFP) said that the first of nine helicopters granted permission to airlift supplies into the delta would arrive in Rangoon on Thursday. “These helicopters will provide critical life-saving capacity to bring urgently needed relief supplies to cyclone victims deep in the delta,” a WFP spokesman said in Bangkok.

However, private citizens who have been doling out aid on the ground in the delta, where torrential rains are compounding flooding from the cyclone, fretted about where they might land. Ko Myo Win, another volunteer, said: “The entire village was in the mud. There was not any hard soil to use as a helipad.”

The permission granted for the WFP helicopters is another sign that the junta is starting to make small, but still unprecedented, concessions to foreign governments and relief agencies appealing for more access to victims. It has allowed aircraft from several countries, including its fiercest critic the United States, to land in Rangoon, although it continues to refuse an American offer to send food from US Navy ships and helicopters in the region.

“We recognise that US citizens by nature are generous and they make generous donations to every region that has come under a natural disaster,” said today's commentary in the New Light of Myanmar. “However, the strings attached to the relief supplies carried by warships and military helicopters are not acceptable to the Myanmar people. We can manage by ourselves."

The generals’ distrust of outsiders is even greater after worldwide outrage at last year’s crackdown on democracy protests. UN sources say that they have consistently declined offers of Thai, Malaysian and Singaporean military helicopters.

In another sign that the junta was taking the disaster more seriously, flags across Burma flew at half mast on the second day of an official three-day mourning period for the victims of the cyclone’s winds and sea surge, which destroyed villages and turned roads into rivers of mud.

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