Bangkok/Yangon  -  Myanmar's death toll from Cyclone Nargis could increase 15-fold to 1.5 million people in coming weeks unless a tsunami-style relief effort is put in place and access granted to international aid workers, the international agency Oxfam said Sunday.

"With the likelihood of 100,000 or more killed in the cyclone there are all the factors for a public health catastrophe which could multiply that death toll by up to 15 times in the coming period," said Oxfam's Regional Director for East Asia, Sarah Ireland.

"We support a call to lift visa restrictions on international aid agencies wanting to assist disaster affected people in Myanmar," said Ireland, joining a growing chorus of relief experts demanding Myanmar's ruling generals grant them visas to expedite a massive emergency aid programme in the areas hard-hit by the cyclone on May 2 to 3, which are only receiving a trickle of supplies a week after the storm.

The cyclone has been described as the worst natural disaster in South-east Asia since the December 26, 2004, tsunami that claimed a quarter-of-a-million lives in Indonesia, Thailand, India and other countries rimming the Indian Ocean.

The tsunami, coming the day after Christmas, sparked an unprecedented outpouring of international aid that was welcomed by the disaster-struck countries.

Myanmar's cyclone has been a different story. While its military regime has welcomed international aid, it blocked the entry of international aid workers all last week, apparently seeking to distribute the aid itself in a cynical publicity stunt.

The cyclone came at a sensitive time politically for the junta, which had planned a referendum on Saturday to win approval of a new constitution that will cement its dominant role under future elected governments through s system of appointees in the upper and lower houses.

Ignoring international appeals to postpone the vote and concentrate on the helping the cyclone victims instead, the military went ahead with the referendum on Saturday, although it was delayed until May 24 in 47 of the worst-hit townships.

International aid workers are growing increasingly frustrated with the generals self-serving strategies in the face of a looming hunger and health crisis in the country, especially in the Irrawaddy delta where the majority of the victims are still without basic supplies because of logistical obstacles and lack of goods.

"In the Boxing Day tsunami 250,000 people lost their lives in the first few hours but we did not see an outbreak of disease because the host governments and the world mobilised a massive aid effort to prevent it happening," said Oxfam's Ireland. "We have to do the same for the people of Myanmar."

Citing evidence from previous experiences in disasters such as the 2004 Indian Ocean tsunami and Pakistan earthquake in 2005, Oxfam said that without an immediate injection of life-saving aid such as clean water sources, up to 1.5 million people are at risk from a diseases such as cholera, typhoid and shigella.

"We are certain the international humanitarian community can make a difference on the ground and that's why we want to work with the people of Myanmar affected by this terrible disaster," said Ireland.

Although Myanmar is still stalling on granting visas to international aid workers, it was permitting the flow of goods into the country.

The World Food Programme (WFP) reportedly flew in three deliveries of high-energy biscuits over the weekend and the UN Human Rights Commissioner (UNHCR) was allowed to send trucks with 20 tons of provisions from Thailand into Myanmar via the Mae Sot border crossing.

Thai King Bhumibol Adulyadej, 80, added to the aid flow on Sunday when he donated 2,000 relief kits valued at over 1 million baht (31,750 dollars) to victims of the cyclone.

The royal donation, including kitchen utensils and bedding material, was transported by a Thai military C-130 aircraft to Yangon Sunday morning. (dpa)