The United Nations has rated the floods in Pakistan as the greatest humanitarian crisis in recent history with more people affected than the South-East Asian tsunami and the recent earthquakes in Kashmir and Haiti combined.

Although the current 1,600 death toll in Pakistan represents a tiny fraction of the estimated 610,000 people killed in the three previous events, some two million more people - 13.8 million - have suffered losses requiring long or short-term help.

Maurizio Giuliano, a spokesman for the UN Office for the Coordination of Humanitarian Affairs (OCHA) said: "This disaster is worse than the tsunami, the 2005 Pakistan earthquake and the Haiti earthquake."

The comparison illustrates the scale of the crisis facing Pakistan as its inefficient and corrupt bureaucracy battles to mitigate the effects of the flooding.

The disaster zone stretches from the Swat Valley in the north, where 600,000 people are in need of help, to Sindh in the south.

Billions of pounds will be needed to rebuild affected areas but western nations have pledged only tens of millions in aid. Radical Islamic groups are jockeying to fill the vacuum left by government incompetence and relative international indifference.

Khyber-Pakhtunkhwa, formerly North-West Frontier Province and scene of a bloody Taliban insurgency, has been devasted by swollen rivers. The steel girder bridge over the Khyali River in Charsadda which built by the British at the height of the Raj is a jagged stump. It was a vital gateway to the region and its loss has hampered the aid effort.

"There are people here who are 80 and who will tell you that they have seen nothing like it in their lives," said Arif Jabbar Khan, leading the Oxfam team in the town. "This was a productive agricultural area with a big middle class who have now lost everything. The effect of that will be enormously destabilizing. There was a riot in town as people demanded food."

Beneath it, the brown waters of the swollen Khyali, three times its normal width, thundered southward over what had been homes and farms.

The problems here are being replicated across Pakistan. Of Khyber-Pakhtunkhwa's population of 1.7 million, some one million have been made destitute by the flooding. The government has managed to distribute 10,000 food packs in the 10 days since the disaster. They will feed just 80,000 people.

Flood victims stand around homeless, aimless, their clothes covered in sticky red mud. The river thunders on, oblivious.

"The reaction in the west to this crisis has been lukewarm so far," said Mr Khan. "The governments there need to understand what is going on." Meanwhile Mr Khan must get on with the basics, pouring chlorine into wells to prevent the spread of e-coli and cholera, and organizing payments to families so that they can buy food in Charsadda's still-functioning market.

The nearby city of Peshawar relies on the area for much of its food, and prices are now rocketing in the markets there - as they are along the length of Pakistan.

Still more people are still dying in Pakistan's remote mountainous northern provinces, swept away in the torrent or buried in landslides.

The government in Islamabad has admitted that it cannot cope with such a catastrophe, but the international response has been lukewarm.

Yousuf Raza Gilani, Pakistan's prime minister, left to deal with the crisis while his president, Asif Ali Zardari, toured Britain and France, said the floods would set Pakistan back years.

Jean-Maurice Ripert, the United Nations special envoy for the disaster, said the scale of funding for Pakistan's recovery could only escalate. He said: "The emergency phase will require hundreds of millions of dollars and the recovery and reconstruction part will require billions of dollars."

Angry survivors have attacked government officials in flood-hit areas. The government's fear of a backlash is believed to be behind the blocking of two independent TV channels, Geo and Ary, which have been critical of President Asif Ali Zardari for going ahead with a European tour as large parts of his country suffered inundation.