Pakistan and United Nations on Tuesday launched a fresh appeal for $440 million to help hundreds of thousands of people rebuild their lives after consecutive years of devastating floods.

The appeal aims to feed people, provide basic services, shelter, health, water and sanitation between now and September in the breadbasket province of Sindh and insurgency-torn Baluchistan, in the southwest.

"This is the funding required for 215 projects," UN Humanitarian Coordinator in Pakistan, Timo Pakkala, told a news conference in Islamabad.

"The emergency is not over yet. Waters may have receded but people are still struggling to restore their livelihood," Pakkala said.

At least 2.5 million people are still without food, water, shelter, sanitation and healthcare, putting them at serious risk of malnutrition, disease and deepening poverty, international charities warned last week.

The floods devastated agriculture and hundreds of thousands of farmers are struggling to recover and a quarter missed the planting season last year because their land was flooded or they did not receive help, they said.

But the disaster elicited a lethargic response from donors. The UN appealed for $357 million last September but only 47 percent of that funding requirement was received.

"It is critical that the international community support this effort to make communities safer, more resilient and better prepared in the event of possible future flooding and other disasters," Pakkala added.

The prime minister's advisor of finance, Abdul Hafeez Shaikh, described the launch as "timely and important" as well as "carefully thought out".

International charities have accused Pakistan of not doing enough to prevent future disasters and prepare for the next monsoon season, only weeks away.

"We have to prepare ourselves better in advance to cope with such disasters in future," Shaikh said.

Pakistan suffers from a poor international image, particularly in the West over accusations that its security establishment still sponsors the Taliban and other Islamist militants, as well as over concerns about corruption.

Its image took a serious decline last May over the discovery that Osama bin Laden had lived for at least five years near the country's elite military academy, until he was found and killed by US commandos.

"I want to assure the international community that we will ensure that things are done in an acceptable and transparent way," said Shaikh.