Britons have donated £4m towards the flood relief effort in Pakistan in less than two days.
The Disasters Emergency Committee (DEC) said the response to Friday's television appeal had been "fantastic".
Millions of people have been affected by the worst floods to hit Pakistan for 80 years, and at least 1,600 have died.
The DEC said that 300,000 people had already received emergency care, clean water, food or shelter as a result of British aid.
DEC chief executive Brendan Gormley 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.
"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."
The TV and radio appeal was presented by journalist John McCarthy, a former British hostage in Lebanon.
International Development Secretary Andrew Mitchell has said the UK government is sending 2,000 all-weather tents to affected districts in Pakistan.
That is in addition to £10m of aid for the country already pledged by British ministers.
The DEC, an umbrella organisation of 13 UK humanitarian aid agencies, urged anyone who has not donated so far to make a contribution by calling 0370 60 60 900 or visiting dec.org.uk.
The DEC charities are ActionAid, Age UK, British Red Cross, Care International, Cafod, Christian Aid, Concern, Islamic Relief, Merlin, Oxfam, Save the Children, Tearfund and World Vision.