USTA MUHAMMAD, Pakistan -- United Nations Secretary-General Antonio Guterres said on Saturday that developing nations were paying a "horrific price" for the world's reliance on fossil fuels, as he toured parts of Pakistan hit by floods blamed on climate change.

Nearly 1,400 people have died in flooding that covers a third of the country -- an area the size of the United Kingdom -- and has wiped out crops and destroyed homes, businesses, roads and bridges.

Guterres hopes his visit will galvanise support for Pakistan, which has put the provisional cost of the catastrophe at more than $30 billion, according to the government's flood relief centre on Friday.

"Pakistan and other developing countries are paying a horrific price for the intransigence of big emitters that continue to bet on fossil fuels," Guterres said in a tweet, shortly before heading to see some of the most flood-affected areas.

"From Islamabad, I am issuing a global appeal: Stop the madness. Invest in renewable energy now. End the war with nature."

Pakistan receives heavy -- often destructive -- rains during its annual monsoon season, which is crucial for agriculture and water supplies.

But downpours as intense as this year's have not been seen for decades, while rapidly melting glaciers in the north have for months heaped pressure on waterways.

'Insanity and suicide'

Before touring flood-affected areas in southern Sindh and Balochistan provinces, Guterres on Saturday said financial help was "not a matter of generosity, it's a matter of justice".

"Humanity has been waging war on nature, and nature strikes back... but it was not Sindh that has made the emissions of greenhouse gases that have accelerated climate change so dramatically."

Guterres has lamented the lack of attention the world has given to climate change -- particularly industrialised nations.

"This is insanity, this is collective suicide," he said after arriving in Pakistan on Friday.

Pakistan is responsible for less than one percent of global greenhouse gas emissions, but is eighth on a list compiled by the NGO Germanwatch of countries most vulnerable to extreme weather caused by climate change.

Around 33 million people have been affected by the floods, which have destroyed around two million homes and business premises, washed away 7,000 kilometres (4,300 miles) of roads and collapsed 500 bridges.

The effect of the torrential rain has been twofold -- destructive flash floods in rivers in the mountainous north, and a slow accumulation of water in the southern plains.

"All the children, men and women are roasting in this scorching heat. We have nothing to eat, there is no roof on our heads," Rozina Solangi, a 30-year-old housewife living in a displacement camp near Sukkur, told AFP on Friday.

"He must do something for us poor," she said of the UN chief's visit.

The meteorological office said Pakistan has received five times more rain than normal in 2022. Padidan, a small town in Sindh province, has been drenched by more than 1.8 metres (71 inches) since the monsoon began in June.

Water levels have reached far higher in areas where rivers and lakes have burst their banks, creating dramatic inland seas.

Thousands of temporary campsites have mushroomed on slivers of high ground in the south and west -- often roads and railway tracks in a landscape of water.

With people and livestock crammed together, the camps are ripe for outbreaks of disease, with many cases of mosquito-borne dengue reported, as well as scabies.