DONORS must “inject urgent funding” to help flood-ravaged Pakistan, Oxfam warned yesterday .

The international community must “step up to the plate” to stop the spiralling crisis, according to the agency, adding that only a fraction of people have received the help they need.

The UK Government has committed £64m to help flood victims in Pakistan, while the appeal by the Disasters Emergency Committee (DEC) has so far raised more than £54m from members of the public.

A new UN appeal is expected to call for a trebling of the $460m raised so far.

And International Development Secretary Andrew Mitchell, who will attend a UN conference on the floods in New York on Sunday, warned now was “not the time to become numb or complacent”.

Oxfam’s humanitarian director, Jane Cocking, said: “This is a crisis of a truly epic scale and it’s far from over yet.

“If the people that need help do not receive it, then disease and hunger could spiral. We desperately need donors to step up to the plate and inject urgent funding.

“These people have lost so much, but they still could lose more.

“Even today, people are drinking dirty and contaminated water straight out of the Indus river. Soon we will need to help them go home and restart their lives.”

Oxfam said almost 4m in need of food aid were yet to receive it.

The charity warned that farmers will miss the planting season, with water yet to recede in some areas, and tools washed away.

The monsoon floods in Pakistan, which began more than six weeks ago, have affected a reported 21m people.

The UN said more than 70% of the flood-affected population lacked access to safe drinking water, and more than 80% lacked access to toilets.

The number of reported cases of acute diarrhoea and skin diseases had more than trebled in the past three weeks, while the number of reported cases of acute respiratory infections had quadrupled.

Ms Cocking continued: “The international community won’t have many chances to show solidarity with people caught up in Pakistan’s floods.

“The UN appeal is one of them and they must seize on it to send a clear signal that they care about the millions affected by this disaster. In turn, aid agencies must challenge themselves and ensure they are doing their utmost to reach all the people that need it.

“Each day, we ask ourselves, are we doing enough? Could we do more? I’d urge all aid agencies to ask themselves the same questions. All of us need to be going at full throttle to have any chance of stemming this mounting crisis.”

Mr Mitchell said: “It is not easy to believe that new towns are still being inundated by flood water more than six weeks after the floods in Pakistan first started; over the last week thousands more people have been forced to leave their homes, many losing all their possessions and livelihoods.

“This is not the time to become numb or complacent. There is an acute need for more help in southern Pakistan, with many towns still under four feet of water, and new towns still being flooded.”

Yesterday, the US envoy to Pakistan, Richard Holbrooke, warned the world will only be able to fund around 25% of the “tens of billions” of dollars needed for reconstruction.

He warned the US Congress might not be generous if it felt Pakistan was not taxing its own citizens enough.