The rush of water spilling from rivers in Punjab has threatened to destroy vast areas of crops, prompting the United Nations to warn that an estimated 1.8 million people might need food aid in the coming weeks.
'We have nothing'
Water levels were so high in large tracts of the Kot Addu area and parts of the south of the province that only treetops and uppermost floors of some buildings were visible.
"We just ran away with our children, leaving behind everything,'' Fateh Mohammad, who was caught by surprise when water breached a protection bank in Kot Addu, said.
"All our possessions are drowned in the water. We have nothing."
People sought refuge on rooftops and tried to bring their livestock up as far as possible.
In the northwest, rising water levels at Warsak Dam, the country's third biggest, prompted disaster officials to ask residents in the northern outskirts of Peshawar city to leave their homes.
"If needed, forced evacuation will be started,'' Adnan Khan, a spokesman for the provincial Disaster Management Authority, said on Tuesday.
Aid workers from Save the Children in the Swat Valley in Khyber Pakhtunkhwa warned that there was a serious risk that violence could break out as food supplies dwindle.
The charity said there had already been skirmishes when food supplies reached Nowshera, one of the hardest-hit districts.
"Families are stranded and desperate for food. There are 40,000 children in the region, many of whom are already going hungry," Matt Wingate, an emergency response leader for the charity, said.
"When aid does get to them the atmosphere can be very tense."
Other relief agencies such as the World Health Organisation were rushing in medical kits to affected areas to deal with diarrhoea.
"When we're talking about kits, we're not talking about small boxes," Al Jazeera's Sohail Rahman, reporting from the Swat Valley, said.
"We're talking about a team of people , like a mini clinic, that can be taken to a town or a village."
He said aid agencies had been facing severe challenges in reaching certain areas, with roads and bridges destroyed, but that repair works on the main road between Islamabad and the northwest had now been completed.
"The highway between Islamabad and Peshawar is now open. That will help the aid efforts, at least getting heavy trucks laden with help from the international community into the provincial capital from where it can be distributed."
A big quantity of aid was destroyed when a UN warehouse in Nowshera was flooded.
The floods have triggered heavy criticism of the government over its response to the disaster.
Asif Ali Zardari, Pakistan's president whose government is already unpopular over widespread allegations of corruption, was criticised for pressing on with a visit to Europe while his country was plagued by disaster.
"Zardari should visit the flood-hit areas and take steps for the welfare of the stranded people instead of taking joy rides to France and the UK," Sher Khan, a villager in Majuky Faqirabad, said.
Many residents who lost their homes and livelihood also complained that they had not received any advance warning that raging waters were heading their way.
But Major General Athar Abbas of the Pakistani army told Al Jazeera that criticism over the state's action was "misplaced".
"There is a deficiency [of aid] because of the magnitude of the calamity," he said.
"We are trying our best, taking into account our limited resources to reach out to a maximum amount of people in a maximum of areas.
"Yes, there are certain areas which were left out. However, so far the rescue operation has been completed and we have gone into a major relief operation, providing provisions to the relief camps as well as medical assistance."
The military said more than 54,000 people had been rescued from flood-hit areas and moved to safer places, with 40 helicopters and 450 army boats mobilised as part of the rescue effort.