ISLAMABAD: Pakistan's unprecedented floods, which have submerged huge swathes of the South Asian nation, have killed nearly 1,500 people, data showed on Thursday, as authorities looked to step up relief efforts for millions affected by the disaster.

The floods brought by record monsoon rains and glacial melt in northern mountains have hit 33 million of a population of 220 million, sweeping away homes, transport, crops and livestock in damage estimated at $30 billion.

The tally of dead stands at 1,486, about 530 children among them, the National Disaster Management Authority said, as it released its first country-wide total since Sept 9, a period that saw 90 more people die.

Over the last few weeks, authorities have thrown up barriers to keep the flood waters out of key structures such as power stations as well as homes, while farmers who stayed to try and save their cattle faced a new threat as fodder began to run out.

The government and the United Nations have blamed climate change for the surging waters, in the wake of record-breaking summer temperatures, that have driven thousands from their homes to live in tents or along highways in the open. 

Pakistan received 391 mm (15.4 inches) of rain, or nearly 190% more than the 30-year average, in July and August. That figure climbed to 466% for one of the worst-affected areas, the southern province of Sindh.

Aid flights from the United Arab Emirates and the United States arrived in the country on Thursday, the foreign ministry said. The United Nations is assessing reconstruction needs.