Monsoon rains have caused extensive flash flooding throughout Pakistan, killing more than a thousand people and causing widespread damage.
Rescuers are struggling to reach 27,000 people still cut off by the floods, which are the worst in 80 years.
"In the worst-affected areas, entire villages were washed away without warning by walls of flood water," the Red Cross said in a statement.
There are fears diarrhoea and cholera will spread among the homeless. Food is scarce and water supplies have been contaminated by the floods.
Donate to the Red Cross Pakistan appeal here.
The Pakistan Red Crescent Society, which has branches and volunteers across the country, has been helping survivors since the flooding began by delivering food, health services, shelter and relief items (including hygiene kits and cooking equipment).
The British Red Cross has donated an initial £50,000 from its Disaster Fund, but the needs are significant and the true scale of the disaster is not yet clear. We urgently need your help to support the relief effort.
I visited the Peshawar region over 20 years ago, the region was beautiful and the people friendly. I traveled overland with a group of people in a truck, London to Nepal, it took about 3 months.
Reading has a large Pakistani community, I am sure they will be concerned about family and friends in the region.
Meanwhile elsewhere in Pakistan the image of David Cameron is being burned, after his speech. Cameron said Pakistan should avoid links with groups that "promote the export of terror". It doesn't sound that controversial to me. He said no-one was in "any doubt" there were terrorist groups operating in Pakistan. Well we know terrorist groups have operated in the UK, Spain & the USA so why would Pakistan be different?
Speaking to reporters after a speech in the southern Indian city of Bangalore on Wednesday, the prime minister said: "We should be very, very clear with Pakistan that we want to see a strong, stable and democratic Pakistan.
"We cannot tolerate in any sense the idea that this country is allowed to look both ways and is able, in any way, to promote the export of terror, whether to India or whether to Afghanistan or anywhere else in the world."
I think part of the problem is that he siad this while in India, which will appear to some to be favouring India over Pakistan in some way. David Miliband has tried to milk his but his own record is so poor he should keep quiet.
In answer to a question about terrorism, Miliband said "yes there are circumstances in which it is justifiable and yes there are circumstances in which it is effective, but it is never effective on its own".
After his trip to India in 2008 following the Mumbai attacks, Miliband wrote in an article that "resolution of the dispute over Kashmir would help deny extremists in the region one of their main calls to arms, and allow Pakistani authorities to focus more effectively on tackling the threat on their western borders". This upset many in India.