Myanmar's ruling junta has opened the door a little wider to foreign aid, allowing more planes with relief and medical supplies to land.

But experts in disaster relief said aid flows were still too little - and increasingly risked being too late as well.

Ms Sarah Ireland, regional director of the agency Oxfam, said compared to other disasters of a similar scale, the response was still 'much too slow'.

Oxfam has allotted US$1.1 million (S$1.5 million) to its aid effort.

But since Oxfam, like many other non-governmental organisations (NGOs), does not have a required agreement to operate inside Myanmar, it is directing aid through its partner organisations with operations in the country - Save The Children and Unicef.

Two flights from the World Food Programme arrived in Yangon yesterday - a day after the first shipment from the agency was reportedly 'seized' by the authorities.

In a statement e-mailed to the Associated Press, government spokesman Ye Htut said the junta had stated their stand and denied that their action amounted to a seizure.

'I would like to know which person or organisation (made these) baseless accusations,' he said.

Myanmar's Foreign Ministry had made it clear on Friday that the government would deliver international emergency aid 'with its own labour'.

In Bangkok yesterday evening, Mr Richard Horsey, spokesman for the UN Office for the Coordination of Humanitarian Affairs in Bangkok, told The Sunday Times: 'We don't know what's happened to (the shipment).'

More relief materials from other sources continued to be delivered to Yangon airport yesterday, including from China, Singapore, Thailand, India and Russia.

The supplies generally comprised tents, mosquito nets, power generators, medicines, instant noodles, high-energy biscuits, clothes and zinc sheets.

One plane-load of medical and relief supplies from the agency Medicins Sans Frontieres (MSF), due to land in Yangon at 8pm local time yesterday, was delayed for seven hours by 'administrative' problems.

Another was to leave the French city of Bordeaux for Yangon once the first had landed and deployed its cargo, which MSF's spokesman in Bangkok Veronique Terrasse said was for use by MSF personnel.

The agency had received all necessary authorisation in relation to the shipment and its use, she said.

Also yesterday, two UN trucks reached Myanmar by land from Thailand, carrying 20 tonnes of materials, including tents and tarpaulins.

Over the last 48 hours, several aid organisations and regional governments also upped aid pledges - including China which added 30 million yuan (S$5.8 million) to its assistance package.

Spokesman Ye Htut insisted the junta were already conducting relief operations 'systematically and orderly' and saw no need for outside assistance beyond donations of cash and relief supplies.

'Myanmar has prioritised receiving emergency relief provisions and is making strenuous efforts to transport those provisions without delay by its own labour to the affected areas,' he said.

nirmal@sph.com.sg