Heavy snow and avalanches have killed up to 200 people in northern Pakistan, bringing the death toll in recent freak weather nationwide to more than 400.
Helicopters are dropping aid to cut-off areas in the north
PM Shaukat Aziz gave the death toll in the north after flying over North-West Frontier Province. Reports of more fatalities were coming in, he said.
More than 200 have died in flooding in south-western Balochistan province, including scores after a dam burst.
Relief work there is focusing on food shortages and preventing disease.
Many roads in North-West Frontier Province are blocked by landslides or snow, hampering aid efforts.
Provincial officials have released 60m rupees ($1m) for relief supplies.
After returning to Islamabad, Mr Aziz said helicopters had been dropping aid to areas cut off.
"The entire machinery of the government has mobilised," he said.
Casualty figures vary widely. Some reports say avalanches near Abbottabad, 60km (40 miles) north of Islamabad, killed 40 on Saturday.
Police in Pakistan-controlled Kashmir say around 50 people have been killed in avalanches there too.
In Balochistan, thousands of troops have been deployed in the relief effort.
Provincial officials say between 200 and 250 people have died in floods, scores after a dam burst near Pasni, 650km (400 miles) from the provincial capital, Quetta.
Five villages were swept away when rains breached the Shadikor dam. At least four other dams have burst.
Between 1,000 and 2,000 people are missing across the province and tens of thousands have been made homeless.
Officials are working to prevent the spread of waterborne disease.
World Health Organisation country director for Pakistan, Khalif Bile, said: "Over the next few days we may see the emergence of serious health problems among the population in the affected areas."
Two C-130 Hercules planes carrying aid were flying to Pasni on Monday with helicopters than transferring packages to villages and districts.
But some villagers complained the relief effort was not working.
One resident of the village of Chalas, Ghulam Yaseen, said only four bags of food were dropped for a stranded population of 500.
President Pervez Musharraf toured the area on Saturday promising financial assistance to people who have lost family members or their homes.
There was further heavy rain in Balochistan on Monday.
Meteorological department director general, Qamar-uz-Zaman, told AFP: "The rains in Balochistan are likely to end Monday night and move towards northern areas and Kashmir, where it will bring more snowfall."