The enormous operation to help those countries worst hit by the disaster, which claimed nearly 290,000 lives, has only just begun, UN Assistant Secretary General Hafiz Pasha said, during a two-day trip to London.

"The relief operation was highly complex involving many different agencies and I think we have managed to avoid the worst case scenario in terms of disease breaking out," Pasha said.

"But now we are beginning to make a transition from the relief to the early recovery stage which will focus on the physical infrastructure -- clearing the rubble and helping people to re-establish their livelihoods," he said.

The United Nations had received some 925 million dollars of the 977 million dollars that it had requested for relief work, according to Pasha.

"But for the reconstruction phase I'm afraid it gets much more expensive -- over the next three to five years we will need between 10-and-12 billion," he said.

At the same time, aid agencies have warned of a shortfall in funds for other emergencies in the world due to a flood of donations for victims of the Indian Ocean earthquake and tsunami that struck on December 26 last.

On Monday, the United Nations food agency, the World Food Programme, said that aid for Africa's starving had plummeted in the wake of the Asian tsunami and pleaded for donors not to let their commitment fall.

Pasha is due to leave Britain on Wednesday to visit the countries most badly affected in order to assess the how well the recovery process is going and to ensure the money pledged is being well spent.

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