Two helicopters carrying flattened rice and molasses left today for one of the worst-hit districts of Western Chapainawabganj, while two missions were carried out yesterday, an air force spokesman said.

``It is very difficult to find a dry patch of land... After a long search the choppers located one high ground,'' the spokesman said.

Authorities had earlier discussed launching air drops but decided against them as they feared hundreds of people could be drowned as they rushed to retrieve aid which will instead be ferried to safer dry ground in worse-hit areas.

More than two-thirds of Bangladesh is now under water. More than 700 people have been killed, 116 of them from diarrhoea which has infected 152,000 people and a quarter of the country's 124 million population has been severely hit.

The United Nationsand the Commonwealth have appealed for urgent aid for emergency relief and initial rehabilitation.

Bangladesh has also requested 879 million dollars in foreign aid, including 240 million dollars' worth of food.

A 50-member US team was expected to be in Bangladesh by Wednesday. Army troops were also aiding flood victims as well as repairing roads and embankments, a spokesman said.