GENEVA, Switzerland — Haiti’s devastating earthquake has left an estimated 3 million people in need of emergency aid, a Red Cross official said today, as aid groups and governments scrambled to send tons of disaster relief to the impoverished Caribbean nation.

Humanitarian officials said the proximity of the quake’s epicenter, only 10 miles (15 kilometres) from the capital Port-au-Prince, and Haiti’s crumbling infrastructure meant it was impossible to gauge how many people might be dead or wounded.

“There’s probably 3 million people potentially affected,” said Paul Conneally, spokesman for the International Federation of Red Cross and Red Crescent societies, basing the estimate on Haiti’s population of 10 million and previous Red Cross experience in earthquake relief.

“Port-au-Prince has been massively impacted,” Conneally said. “There are many, many people trapped in the rubble.”

The neighboring Haitian cities of Carrefour and Jacmel may also be heavily damaged, said Elizabeth Byrs, a United Nations humanitarian spokeswoman.

The Red Cross said Haiti’s disaster relief teams were “completely overwhelmed.”

“There’s no structured response at this point,” spokesman Simon Schorno told The Associated Press.

The first airlifts to Haiti were concentrating on search and rescue efforts, setting up makeshift hospitals and delivering food.

United States Secretary of State Hillary Rodham Clinton said the US was offering full assistance — civilian and military — while Britain, France, Canada, Germany, China, Mexico and Venezuela pledged immediate support in terms of personnel, cash and supplies.

One of the first teams expected to arrive Wednesday in Haiti was 37 search and rescue specialists from Iceland, along with 10 tons of rescue equipment.

French rescue authorities said 65 rubble-clearing specialists and 6 sniffer dogs were leaving Wednesday for Haiti, while Spain was rushing three airplanes there with at least 100 tons of tents, blankets and cooking kits. Israel was sending in an elite Army rescue unit of engineers and medics.

Some aid flights from Europe were delayed by heavy snow. A British plane with 64 firefighters and rescue dogs was grounded temporarily at Gatwick airport.

Spain said it would provide €3 million (US$4.3 million), the Netherlands pledged €2 million ($2.9 million), Germany, €1 million (US$1.45 million) and China, US$1 million.

UN officials were struggling to assess the scale of the disaster amid badly damaged communication networks and were working with aid agency Telecoms Sans Frontieres to get phone lines working again, Byrs said.

There was no electricity in the capital and roads were filled with rubble and debris, she said, adding that Port-au-Prince’s airport remained open but the artery connecting it to the city was blocked.

Irish telecommunications company Digicel said it was donating $5 million to aid agencies working in Haiti. The company — a major cell-phone operator in the Caribbean — also was sending specialists there to help repair the damaged phone network.

UN agencies and Red Cross societies were trying to send in teams and aid from their regional hub in Panama, while USAID was mobilising experts and two urban rescue units, Byrs said.

If aid cannot travel over the airport road to the Haitian capital it may be rerouted through the Dominican Republic, said Charles Vincent, a senior World Food Program official. His agency planned to airlift 86 tons of high-energy biscuits from El Salvador, enough to feed 30,000 people for a week.

“The first priority is to save lives,” Vincent told reporters.

Conneally said the emergency shelter and long-term rebuilding efforts could easily require a year of aid work.

At the Vatican, Pope Benedict XVI appealed for a generous aid response for the quake victims and pledged the Catholic Church’s support.

The Christian aid organisation World Vision, which has 400 staff in Haiti, said it would immediately distribute the hurricane relief supplies it had stored there.

Low-lying areas of Port-au-Prince, including the Cite Soleil slum, appeared to be hit worse than neighbourhoods higher up the hills, World Vision spokesman Casey Calamusa said.

Maggie Boyer, the World Vision spokeswoman in Haiti, said the moment the quake hit felt “like a truck had run into her building,” he added.