Record monsoon rains and melting glaciers in Pakistan’s northern mountains have brought floods that have affected 33 million people and killed at least 1,314 by official government figures.
More international support is needed as the relentless extreme weather continues to displace vulnerable families, campaigners said.
Khuram Gondal, Save the Children’s national director for Pakistan, said: “With each new day the impact of this horror show just gets worse and worse.
“Today’s news is yet another reminder that children are some of the most vulnerable to extreme weather events that are becoming more and more deadly due to the climate crisis.
“We dread the coming days in which we may hear even worse news – particularly if we cannot get lifesaving aid to people in time.”
The UN’s refugee agency rushed in more desperately needed aid to the flood-stricken country on Monday as Pakistani prime minister Shahbaz Sharif traveled to the south where rising waters of Lake Manchar pose a new threat.
On Sunday, engineers cut into an embankment in the sides of Lake Manchar in an effort to release rising floodwater to save the city of Sehwan and several nearby villages from possible destruction by flooding waters.
Mr Sharif was met by Bilawal Bhutto, the foreign minister, in the city of Sukkur on the swelling Indus River, from where they toured the flood-hit areas by helicopter. Murad Ali Shah, the province’s chief minister, briefed Mr Sharif about the damages caused by floods in Sindh province.
Floods have caused $10bn (£8.7bn) in damage since June, according to government estimates. The provinces of Punjab, Sindh, Baluchistan and Khyber Pakhtunkhwa have been the most affected and the majority of people killed there were women and children.
Afghan refugees living in Pakistan have also been affected by the floods. More than 420,000 Afghan refugees are estimated to be in the worst-affected areas.
Last week, the United States announced $30m (£26m) in aid for Pakistani flood victims. The UK has announced £15m in aid and the EU €1.8m (£1.55m).
Mr Gondal said the aftermath of the floods will bring even more risks to children, including disease, hunger, lack of healthcare and safeguarding risks.
“Many children are now wandering around on their own, have lost their homes and their families, vulnerable to horrors like trafficking.
“We urgently need more support from the international community. And the world must wake up to the climate emergency and its deadly threat to children.”