The international aid effort in parts of the Philippines devastated by Typhoon Haiyan is starting to have a major impact, with tens of thousands of victims receiving supplies.
Medical teams are operating in the worst-affected areas and US helicopters flying aid to isolated settlements.
The UN says it and its partners hope to provide enough aid for six months.
Haiyan, which hit eight days ago, has killed more than 3,600 people and left about half a million homeless.
Patrick Fuller of the International Federation of the Red Cross told the Associated Press news agency: "At the moment we are ramping up a major relief effort and the supplies are coming in."
Mr Fuller - who is in Tacloban, one of the worst-hit areas - said: "We're setting up an emergency response hospital here, water and sanitation units." However, he added that people in affected areas would need long-term "support with rebuilding".
Both the Red Cross and the medical charity Medecins Sans Frontieres (MSF) said they would have mobile surgical units up and running in Tacloban by the end of the weekend.
US Navy helicopters have been dropping food, water and other supplies from the aircraft carrier USS George Washington, which arrived off the coast on Thursday.
The carrier is also expanding search-and-rescue operations. The US military said it would send about 1,000 more troops along with additional ships and aircraft to join the aid effort.
Britain will give an extra £30m ($50m) in emergency aid, bringing UK assistance to £50m, Prime Minister David Cameron announced. The UK Disasters Emergency Committee (DEC) said donations from the public had reached £33m.
Although a huge international aid effort is under way, widespread infrastructure damage is hampering efforts to distribute it to some areas.
Desperate survivors are still trying to leave the coastal city of Ormoc, 105 km (65 miles) west of Tacloban, Reuters news agency reports.
Philippine Social Welfare and Development Secretary Corazon Soliman acknowledged in a radio interview that the national relief response had been too slow to reach many areas.
"We will double our efforts to distribute relief goods because we've been hearing complaints that a lot of people have yet to receive relief goods," she said.
About 11 million people have been affected by Typhoon Haiyan, according to UN estimates.
It was one of the most powerful storms ever recorded on land, with winds exceeding 320km/h (200 mph) unleashing massive waves. Tacloban's airport was left in ruins.
Health experts have warned that the worst-affected areas are entering a peak danger period for the spread of infectious diseases.
The Philippines National Disaster Risk Reduction and Management Council said that as of 10:00 GMT on Saturday, 3,637 people had been reported dead, 12,501 injured and 1,186 missing. The death toll is expected to rise as further assessments are made.