Relief groups and international aid workers are struggling to deliver aid to the survivors of Haiti's devastating earthquake. Fears of unrest are also spreading as the nation begins to face its fifth day of desperation.

The global helping hand has been slowed by the capital's damaged seaport and airport. The airport turned away civilian aid planes for eight hours on Thursday because of a lack of space and fuel.

Aid workers have also been blocked by debris on inadequate roads and by survivors, gathered in the open, fearing aftershocks from the quake.

Countless dead remain unburied. Hard-pressed government workers have been burying thousands of bodies in mass graves. Increasingly the focus is now the daunting challenge of getting aid to survivors.

The UN has launched an appeal late Friday for 550 million US dollars to provide essentials for Haitians. Secretary-General Ban Ki-moon said on the same day that the humanitarian effort is underway.

Ban Ki-moon, UN Secretary-General, said, "A high proportion of the three million people in the capital area are without access to food, water, shelter and electricity. We are still in the search and rescue phase, and we are trying to save as many lives as possible. A major humanitarian effort is now well underway."

As thousands of people wounded in the earthquake continue to seek medical attention, aid group Medicines San Frontieres has turned their Port-au-Prince headquarters into a makeshift hospital.

The charity says they have treated at least 1500 patients at locations across the country but that transport blockages have prevented medical supplies from getting through quickly enough.

The organization says all of its three existing medical facilities have been partially damaged and that most patients are being treated in tented clinics nearby.