Mark Dummet explains the World Food Programme's food mission (8 May)
A plane carrying UN relief aid from Bangladesh to cyclone victims in Burma has landed in the capital, Rangoon.
Aid agencies say the cargo was impounded on arrival after the World Food Programme won permission from Burma to send the shipment.
Two planes carrying aid supplies organised by Bangladesh's army have already been sent.
The UN says it is disappointed at the slow progress made in securing access to victims of the cyclone.
It says about 23,000 people have died in the storm and tidal surge and 1.5 million are at risk.
Burmese state media say 22,980 people were killed by Cyclone Nargis but there are fears the figure could rise to 100,000.
While flights from Western agencies have been held up, however, Burma's regional neighbours, including India and Thailand, have already flown in aid.
The World Food Programme has sent one shipment of high energy biscuits to Rangoon and has received clearance for a second larger one.
In all it says it will send half a million packets of the biscuits to Burma.
They have proved helpful in other emergencies, such as the cyclone which struck Bangladesh six months ago, destroying or damaging the houses of more than a million people.
The BBC's Mark Dummett in Dhaka says Bangladesh has stockpiles of emergency aid because of the frequency with which natural disasters strike the country.
There are also hundreds of aid workers in Bangladesh with the experience of coping with the aftermath of a cyclone.
But some agencies say the Burmese embassy has been slow in issuing visas.
India has already sent two ships, loaded with food, medicines and equipment for the cyclone victims.
India has improved its ties with the Burmese military regimes in recent years.
Correspondents say this may explain why it is one of the first countries to rush aid to Burma without feeling apprehensive about its acceptance.