Hundreds of thousands of Pakistanis have been forced to flee their homes after a major river in the south of the country burst its banks.
A surge of floodwater smashed two flood barriers along the river Indus displacing at least 175,000 in the city of Thatta alone.
More than 8 million people are thought to be in need of emergency aid across Pakistan after weeks of monsoon rains.
But the UN believes the latest breaches have resulted in a further million victims being left without shelter.
The official number of dead stands at 1,600 but that figure is expected to increase significantly.
Despite orders to leave danger zones many have decided to stay put.
One flood victim said: ‘‘We are taking refuge in this graveyard. We don’t have enough food and clean drinking water here. Our children are hungry and no one from the government is taking care of us. We left everything in our houses.”
In a development likely to complicate relief efforts the UN says it plans to review security after the Taliban issued a veiled threat against aid workers helping the relief effort.