About 85% of homes have been flattened

The United Nations Office for the Co-ordination of Humanitarian Affairs has confirmed 700 people are known to have died.

The cyclone struck two days ago with winds reaching more than 150 kms per hour, and the death toll is expected to rise to thousands.

The UNOCHA said the fate of several thousand fishermen in canals and inlets of small islands south of Bangladesh are not known.

One hundred bodies have been found near Dublarchar Island, 90 km off the coast.

Relief workers have described scenes of "complete devastation".

An estimated 85% of village houses, usually made from bush materials, have been flattened.

Thousands of people have been displaced and many are taking refuge in stone buildings such as schools and mosques.

Many have been injured from falling walls or live electric wires.

Relief workers now fear disease could ravage the country as running water has become polluted and many are suffering with gastric illnesses.

The tidal waves have swamped most of the tube wells.

John Key, field director of World Vision, told the BBC the rice fields, which are a lifeline to people in the area and were due to be harvested, have been completely wiped out.

He said people are distressed because they do not know the fate of loved ones.

But he also said hunger is now a growing problem.

"My top priority is to get my World Vision relief teams on the spot with supplies of food for the families concerned. That is going on right now - at least we can sustain life," he said.