Lack of electricity to the control tower at the airport in Port-au-Prince, Haiti's capital, meant relief planes were restricted to radio-assisted, line-of-sight landings, a spokeswoman for the U.N. for the Coordination of Humanitarian Affairs, told The New York Times.
"It is going to be a major logistical challenge," Elisabeth Byrs told the Times in an article published Thursday.
Florian Westphal, a spokesman for the International Committee of the Red Cross, said some planes landed but there was no personnel to unload them and "little security."
"The big challenge is going to be getting things unloaded and getting it to the people who need it," he said. "Only military airplanes that don't require additional people to unload have been able to land."
Douglas Alexander, Britain's international development secretary, said Britain sent 71 rescue specialists with dogs and lifting equipment, coordinating its effort with U.S. and European authorities.
French officials said France would send three military transport planes filled with aid supplies and 100 troops based in the French West Indies, the Times said.
German Foreign Minister Guido Westerwelle said Thursday Berlin would provide "every possible help" to Haiti.
China said it sent a 60-member search-and-rescue team with sniffer dogs to Haiti and the Red Cross Society of China said it would donate $1 million in emergency aid.