HUNDREDS of US troops have surged into Haiti's quake-ravaged capital to guard convoys and food distribution sites, while thousands more stationed themselves on ships and helicopters offshore to bolster relief and recovery efforts.

One week after a 7.0-magnitude quake crippled Port-au-Prince, many Haitians living on the streets had still not received any food or medical assistance from their Government or the international community. But there were increasing signs that the aid effort was gaining momentum.

The Haitian government said 75,000 people had been killed in the quake, with another 250,000 injured and more than a million left homeless.

As the UN Security Council approved 3500 additional peacekeepers for the Haiti mission, the US military and other foreign forces began dropping food from planes, delivering troops by helicopter to volatile neighbourhoods, and working to prepare other entry points for aid deliveries.

The delivery of aid was still hampered in some cases, leading to frustration among Haitians and the workers trying to help them.

The medical organisation Doctors Without Borders said that another of its cargo planes had been diverted from landing at the Port-au-Prince airport, where officials have struggled to cope with the massive influx of aid. The group said it has had five flights carrying medical supplies refused landing so far.

Major-General Daniel Allyn, second in charge of the US military operation in Haiti, said officials ''continue to make progress'', but added: ''We do not underestimate the scope of the challenge here.''

General Allyn said troops were working to open more airfields, get more trucks to help deliver water and supplies to victims, and bring in repair and construction equipment to start removing rubble.

As of Tuesday morning, General Allyn said, there were about 2000 US soldiers on the ground and about 5000 on ships or helicopters offshore helping in the efforts. The US military is eventually expected to have 10,000 troops involved in the operation - with half of them coming ashore.

US and Canadian military forces have been charged with guarding food distribution sites as they open, freeing the UN security forces to patrol and keep order.

The additional UN peacekeeping personnel approved on Tuesday will bring the total in Haiti to 12,500.

Throughout the morning, US Navy Black Hawk helicopters shuttled in troops to the badly damaged National Palace compound in the centre of the city.

US troops had been dropping food and water from helicopters in various locations, but doing so had created mayhem as Haitians scrambled for the supplies. UN aid officials have advised against the practice after one drop near the slum of Cite Soleil almost caused a riot.

Among the many supplies running short in Haiti is blood, a World Health Organisation official said.

''Haiti's National Blood Centre building was damaged and some equipment may need to be replaced,'' he said.

Business owners began visiting shops and warehouses in the city centre, hoping to secure what inventory was left. But only a small contingent of Haitian police, unassisted by foreign forces, worked to hold back increasingly impatient crowds awaiting food, water and international help.

WASHINGTON POST, NEW YORK TIMES