PORT-AU-PRINCE - Thousands of people left hurt or homeless in Haiti's earthquake begged for food, water and medical assistance on Friday as the world rushed to deliver aid to survivors before their despair turned to anger.

Tens of thousands are feared dead from Tuesday's massive quake. The Pan American Health Organisation estimated the death toll could be 50,000 to 100,000, higher than previous figures from the Haitian Red Cross, which saw deaths at up to 50,000.

 Citizens in the wrecked coastal capital Port-au-Prince spent a third night sleeping out in the open on sidewalks and streets strewn with rubble and scattered decomposing bodies, as aftershocks rippled through the hilly neighbourhoods.

Governments across the world were pouring relief supplies and medical teams into the quake-hit Caribbean state, already the poorest in the Western Hemisphere. But huge logistical hurdles and the sheer scale of the destruction meant aid was still not reaching hundreds of thousands of victims.

"We have lost everything. We are waiting for death. We have nothing to eat, nowhere to live. We have had no help. No one has come to see us," said quake victim Andres Rosario, speaking at an improvised camp set up by survivors at a rubbish dump in Port-au-Prince.

"No one is helping us. Please bring us water or people will die soon," said another resident Renelde Lamarque, who has opened his home yard to about 500 quake victims in the devastated Fort National neighbourhood.

Raggedly-dressed survivors held out their arms to foreign reporters in the streets, begging for food and water.

Amid fears that local anger and frustration over delays in receiving help could explode into violence, U.S. Defence Secretary Robert Gates said that aside from some scavenging for supplies and minor looting the security situation on the ground in Haiti remained "pretty good."

"The key is to get the food and the water in there as quickly as possible so that people don't in their desperation turn to violence or lead to the security situation deteriorating," Gates told reporters in Washington. The United States is leading a massive international relief effort.