Rescue and relief activity is continuing in flood-ravaged Pakistan where the death toll has climbed to over 1,400, and three million people have been affected so far.

A spokesperson for the UN Children's Fund said 1.3 million people were severely affected by the floods in the northwest, triggering heavy criticism of the government over its response to the disaster.

Pakistani authorities are struggling to help victims of the flooding, many of whom have lost their homes and livelihood and say they had not received any official warnings that raging waters were heading their way.

Gul Abad village at Charsadda town is one of the many villages that were washed away with torrential rain and heavy flooding.

"It was raining last night and we sat in the open like we are at the moment. We receive some relief goods, the others we don't. But we are in desperate need of tents and shelter," said Saeed Jan, a young man whose house was completely destroyed by floods.

Others said they weren't getting enough food: "The ration comes. The village elders give it out to their own people, poor get nothing. Ration officials demand identity cards. Where can we produce identity card from? We lost those cards with our belongings. So, we are facing difficulty," said villager Sher Wali.

Authorities expect the death toll to rise, with forecasts of more of the heavy monsoon rains that have been lashing the area for the past week.

Officials have expressed concern that waters were spreading from the worst hit province of Khyber Pakhtunkhwa to Pakistan's Punjab heartland, the major food-producing province.