KARACHI: Authorities were Monday racing to protect two southern towns and their 360,000 residents from surging floods, as the nation struggles to cope with its worst natural disaster in living memory.

A month-and-a-half after monsoons caused devastating floods throughout the country, submerging an area the size of England, eight million people remain dependent on handouts for their survival, which many say are too slow coming.

Advancing floodwaters continue to threaten towns in Sindh province, where 19 of its 23 districts have been deluged, displacing more than 2.8 million people, according to provincial authorities.

“The situation is a bit serious in Johi town and Dadu. We are taking all-out measures to save them from ravaging floodwaters,” provincial irrigation minister Jam Saifullah Dharejo told AFP.

“The water is 20 kilometres away from Dadu city but we cannot rule out a serious threat to this city,” one of the largest in the north of Sindh, Dharejo said.

“We are making all our efforts to save Dadu and Johi,” he added.

Dadu and Johi are about 320 kilometres north of Karachi and officials fear the waters will breach protective embankments unless they are quickly strengthened.

“Things are getting serious, we have employed all the possible resources on the embankments to save the remaining towns and villages of Dadu district,” Dharejo said.

District coordination officer Iqbal Memon said Johi was more in danger from the advancing floods.

“The floodwaters are fast heading towards Johi town after inundating most parts of Khairpur Nathan Shah and Mehar towns and several surrounding villages in Dadu district,” he said.

“For two days, we are employing all available means to strengthen the protective embankments around Dadu and Johi but the threat still remains,” he said.

About 80 per cent of the Johi's population of 60,000 had already fled to safer areas. Memon, however, asked the 300,000 residents of Dadu not to panic.

“The people of Dadu city should remain vigilant for any serious situation that could come across,” he said.

The UN has warned that the slow pace of aid pledges could impede relief operations and says Pakistan faces a triple threat to food supplies -- with seeds, crops and incomes hit.

The floods have ruined 3.6 million hectares of rich farmland, and the UN's Food and Agriculture Organisation said farmers urgently needed seeds to plant for next year's crops.

Prime Minister Gilani has warned that the country faces inflation of up to 20 per cent and slower growth because of the disaster.

The floods have killed 1,760 people but disaster officials have said the number of deaths is likely to rise “significantly” when the missing are accounted for.