Duncan Hewitt, reporting from Beijing: "The disruption to normal life is immense"

A Communist Party document, described as an emergency circular, urged local governments to enforce order in areas where flood victims are gathered.

It called for frequent police patrols and for public security staff to protect stations, ports, key traffic lines and warehouses.

The document said there should be severe punishments against robbers taking advantage of the flood situation.

It also urged a clampdown on anyone involved in what it calls market manipulation - where prices of rice and vegetables have risen dramatically as traders seek to capitalise on food shortages.

Thousands dead

More than 2,000 people have been killed so far in what officials are calling China's worst flooding since 1931.

While the situation around the central Yangtze river remains critical, torrential rains and flooding are now afflicting the north-east of the country.

More than 14 million people have been displaced from their homes by flooding, most of them along the middle reaches of the Yangtze.

Far to the north, in inner Mongolia, another 750,000 people are reported to have been affected.

With millions of hectares of crops destroyed and many people unlikely to be able to return to their homes for weeks or months, aid agencies have warned that the food situation could become a growing problem.

This is a major concern for the government, which has set up a donation hot-line. According to reports, $1.5m has already been pledged in its first two days.