Bottlenecks and infrastructure damage have been holding up aid efforts in Haiti, where Tuesday’s earthquake has left as many as 45,000-50,000 dead.

There is little sign of humanitarian supplies beyond the Port-au-Prince airport, and correspondents say there is increasing anger among survivors.

Many are spending a third night without shelter in the ruined capital.

A US aircraft carrier is due to arrive off the coast of Haiti to help co-ordinate the movement of supplies.

President Barack Obama pledged a huge aid effort, but warned it would take time for help to reach people.

‘Nothing coming’

But on the ground, correspondents said there was little immediate sign of a co-ordinated relief effort.

Planes queued to land at the airport, while the port was too damaged to use. Roads were blocked by debris.

The BBC’s Andy Gallacher in Port-au-Prince says those that survived the massive earthquake are now dying in huge numbers, and clean water, food and medical supplies are desperately needed.

Bodies piled up on the streets and bulldozers were being used to remove the dead, and there is mounting frustration and anger.

“We hear on the radio that rescue teams are coming from the outside, but nothing is coming,” said one man, Jean-Baptiste Lafontin Wilfried.

Haiti Quake

“Unfortunately, they’re slowly getting more angry and impatient,” said David Wimhurst, a spokesman for the Brazilian-led UN peacekeeping mission in Haiti.

“We’re all aware that the situation is getting more tense as the poorest people who need so much are waiting for deliveries.”

The UN headquarters has collapsed and correspondents say there is little official presence in Port-au-Prince despite reports of looting.

“Our biggest problem is insecurity,” Delfin Antonio Rodriguez, the rescue commander from the neighbouring Dominican Republic, told AFP news agency on Friday.

“Yesterday they tried to hijack some of our trucks. Today we were barely able to work in some places because of that.”

Shaul Schwarz, a photographer for Time magazine, told the BBC he had seen a roadblock formed with bodies of quake victims on a main road, south of the capital.

He said he believed this was an “act of anger” on the part of people who are not getting help.

Haitian former President Jean-Bertrand Aristide, who has been living in exile since he was ousted in 2004, has offered to return to take part in the reconstruction efforts.

Race against time

The Red Cross estimates 45,000-50,000 people have died since Tuesday’s earthquake.

It estimates that, in total, up to three million people in Haiti have been affected.

Speaking in Washington on Thursday, Mr Obama said some US rescuers were already on the ground in Haiti and more were on their way.

He promised the country “every element of our national capacity, our diplomacy, and development assistance”.

Mr Obama also pledged an immediate $100m for Haiti’s relief effort and said that investment would grow over the coming year to aid long-term recovery.

The USS Carl Vinson aircraft carrier and the USS Bataan, carrying a marine expeditionary unit, are on their way to Haiti.

Gen Douglas Fraser, head of the US Southern Command, told reporters that logistics would be the key to providing relief and that US forces would strive to make Port-au-Prince’s port functional again.

Aid groups say it is a race against time to find people trapped under the rubble of collapsed buildings.