The British public has donated £4 million towards the flood relief effort in Pakistan.
Response to a TV appeal aired less than 48 hours ago has been "fantastic", the Disasters Emergency Committee (DEC) said.
The money raised will go towards helping the 12 million people affected by the worst floods to hit Pakistan in 80 years.
It is estimated that around 1,500 people have so far died as a result of the heavy monsoon rains which arrived in the region last Saturday.
Millions more have been left homeless or are living in cramped and squalid conditions while awaiting assistance.
The DEC said some 300,000 people have already been provided with emergency care, clean water, food or shelter as a result of British aid.
But it urged anyone who has not yet donated to do so by calling 0370 60 60 900 or visiting dec.org.uk.
Brendan Gormley, chief executive of the DEC, said: "As always the British public have shown themselves to be extremely generous. Despite the tough economic times, the public response has been fantastic and the donations we have received are now having a real and immediate impact on people who have been affected by the flooding."
He added: "Although the situation in Pakistan is difficult with waters having washed away or severely damaged bridges, roads and railway tracks, the aid is getting through and reaching those who need it most.
"Aid agencies are already distributing life saving medical supplies, clean water and food parcels."