UN Secretary-General António Guterres appealed to the world for massive help for Pakistan on Friday as he arrived to support its response to a flood disaster that both he and the government have blamed on climate change.

Record monsoon rains and glacier melt in northern mountains, have triggered floods that have swept away houses, roads, railway tracks, bridges, livestock, and crops, and killed more than 1,391 people.

Huge areas of the country are inundated and hundreds of thousands of people have been forced from their homes. The government says the lives of nearly 33 million people have been disrupted.

"I appeal for massive support from the international community as Pakistan responds to this climate catastrophe," Guterres said upon arrival.

He was due to meet Prime Minister Shehbaz Sharif and visit inundated areas on his two-day visit.

The United Nations has launched an appeal for US$160 million in aid to help Pakistan cope with the disaster though Pakistan estimates the floods have caused losses of about US$10 billion.

As well as meeting Sharif and foreign minister Bilawal Bhutto Zardari, Guterres will tour affected areas during his visit.

"This visit will make the world better understand the devastation caused by the floods," Information Minister Marriyum Aurangzeb said in a statement.

In July and August, Pakistan got 391mm of rain, or nearly 190 percent more than the 30-year average.

The southern province of Sindh has seen 466 percent more rain than average.

The World Health Organization has said more than 6.4 million people need humanitarian support in flooded areas.

- Reuters