Relief has still not reached large sections of Haiti's population [AFP]

A massive international aid effort is gathering momentum in Haiti in the aftermath of a deadly earthquake, but the bulk of survivors are still going without food, medicine and proper shelter nearly a week after the disaster struck. 

Two-thousand US marines were due to arrive in the Haitian capital, Port-au-Prince on Monday, to bolster the 1,000-strong US force already in place as part of an international relief and security effort.

The race to deliver aid comes amid growing desperation among hapless victims of last Tuesday's 7.0 magnitude earthquake.

Aid supplies were just starting to reach those most in need due to a bottleneck at the capital's small airport - the main entry point for assistance pledged by world leaders after the disaster.

Al Jazeera's Rob Reynolds, reporting from the Haitian capital, said the much criticised bottleneck had started to improve by Monday.

Critical fuel shortage

But he said a shortage of fuel continued to hamper efforts to deliver the aid.

"Fuel is running very short here, at the gas stations there is nothing. Haitians sometimes are lining up at the gas stations just on the hope that something will appear," he said.

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"The UN is bringing in 37,000 litres of fuel from the Dominican Republic, but the roads between Santo Domingo and Port-au-Prince are now so crammed with vehicles that it is taking about 18 hours to get in, if not more."

Al Jazeera's Teresa Bo, also reporting from Port-au-Prince, said quake survivors in the capital were growing increasingly frustrated over what appeared to be the mismanagement or miscommunication that was holding up the aid.

In the absence of large scale foreign help, Haitians were trying to help each other, she said, with some turning homes into hospitals to treat the wounded and others giving away food.

Sporadic violence

Frustration over aid delivery turned to anger in some places, as Haitian police struggled to keep the peace.

Al Jazeera's Zeina Khodr, also in the Haitian capital, said violent incidents have been sporadic, but Haitian police are out in force patrolling the streets.

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Meanwhile, Lieutenant-General Ken Keen, the US army general who is leading the military relief effort in Haiti, said the security situation is better than it was before the earthquake.

"My assessment of the security situation is that it is calm at this time," he said.

"There are incidents of violence but those who live and work here in Haiti, who have been here for years both within our embassy and the other international community ... tell me that the level of violence that we see now is below pre-earthquake levels."

Meanwhile the European Union pledged over $575m in emergency and long-term aid, the bloc said on Monday.

The union is also moving towards sending 150 people to assist the police force and help beef up security, as tensions in the Caribbean nation rise.

There were some signs of progress on Sunday as international medical teams took over damaged hospitals and clinics where injured and sick people had lain untreated for days.

A few street markets had begun selling vegetables and charcoal in the capital and US officials said international search teams had rescued at least 61 people from the rubble of flattened buildings so far.

Hundreds of lorries carrying aid and guarded by armed UN patrols streamed from the airport and UN headquarters out into the city but they were soon obstructed on streets clogged with people, debris and vans carrying coffins and bodies.

There were also scrums for food and water as UN lorries distributed food packets and US military helicopters dropped boxes of water bottles and rations.

Ban Ki-moon, the UN secretary-general, who visited Port-au-Prince on Sunday, said the situation in the country was "one of the worst humanitarian crises in decades".

Amid shouts of "where is the food? Where is the help?" from survivors, Ban appealed to the Haitian people "to be more patient".

Haitian government officials say 70,000 bodies have already been buried in mass graves and estimate the total death toll to be between 100,000 and 200,000.

Source: Al Jazeera and agencies