"Given the humanitarian crisis we felt the need to continue the supplies," said Marcus Prior, a spokesman for the WFP in Bangkok.
On Friday, Burma authorities at Rangoon International Airport refused to hand over several tonnes of high-energy biscuits to WFP officials for distribution to hundreds of thousands of people desperately in need of food as a result of Cyclone Nargis.
"My understanding is that basically they wanted to distribute the food themselves," Prior told Deutsche Presse-Agentur dpa.
While the WFP hashes out terms with Burma's military regime by which the emergency supplies may be released, the agency has allowed another three air shipments of supplies to Rangoon, scheduled to arrive Saturday and Sunday.
The WFP generally tries to distribute disaster relief through its own personnel, but has made exceptions in the past in such countries as Ethiopia and North Korea.
"There is flexibility but for our credibility we need to be accountable to our donors," said Prior. "We need to provide an assurance that the food gets to the people in need."
Burma's rulers also have their credibility at stake. The junta went ahead with a referendum on a new constitution Saturday designed to cement their political dominance over future elected governments.
The cyclone, which may have killed as many as 100,000 people and left up to 1.9 million in need of emergency aid, has come at an awkward time for the regime.
The country's 400,000-strong military has been given the double task of monitoring the referendum Saturday while at the same time taking the lead in the distribution of emergency aid.
United Nations Secretary General Ban Ki-moon in a statement on Thursday urged the regime to postpone the referendum to concentrate on the "national tragedy," but the regime has ignored his request.
Meanwhile, delays to the aid programme thrown up by the regime are increasing the risks of national catastrophe in the country, especially in the Irrawaddy delta that was hardest hit by the storm.
International aid organisations warned Friday that diphtheria, cholera and malaria could spread in an epidemic of "apocalyptic proportions" if medical, food, water and other types of aid are not allowed to land, along with trained personnel to administer the support.
While the government has confirmed 23,000 deaths and another 42,000 missing, UN officials on Friday estimated the death toll will climb to 63,000 to 100,000 based on reports from 18 aid organisations working in 55 devastated Burma townships.
One sign that the Burma government was more open to receiving aid, it gave permission to a US military aircraft to make one C-130 cargo plane delivery on Monday, Gordon Johndroe, spokesman for the National Security Council, said.
The International Federation of the Red Cross (IFRC) in Geneva said humanitarian aid had reached around 220,000 people, despite logistical difficulties.
The UN said it had received pledges of 77 million dollars out of the total of 187 million dollars that it has asked for to fund international relief efforts.//dpa