Bottlenecks in the aid pipeline remained, but a top UN official said these were being overcome more quickly than in previous disasters.

The US military announced plans to double to about 90 the number of helicopters it was providing for the aid effort, boosting the capability to supply badly damaged areas where airplanes cannot land.

"We are making extraordinary progress in reaching the majority of the people affected in the majority of the areas. We are also experiencing extraordinary obstacles in many, many areas," UN Emergency Relief Coordinator Jan Egeland said at a news conference.

He said donations toward disaster relief were growing daily, and "we are somewhere between $2 billion and $3 billion in total pledges," including funds intended for longer term reconstruction.

One aid agency, Medecins Sans Frontieres (Doctors without Borders), urged donors to stop sending it money for tsunami victims, saying it had collected enough funds to manage its relief effort in the region. The French government reacted by urging people to keep on giving.

Rich industrialized nations, criticized in the early days of the crisis for what was seen as an inadequate response, have stepped up efforts to help countries devastated by the tsunami by offering to freeze billions of dollars in debt repayments.

Britain's finance minister, Gordon Brown, said this could lead to "the possibility of some write-off of debt."

In Washington, Congress was expected to approve more aid on top of the already announced $350 million US contribution.

"I intend to ensure that aid is flowing as efficiently and effectively as possible," said Senate Majority Leader Bill Frist, a Republican from Tennessee.

Germany was expected to boost its aid contribution from $27 million to $680 million, according to a government source, which would make the country the biggest single contributor to relief funds. Chancellor Gerhard Schroeder promised to announce "a significant sum" on Wednesday.

He was a little upstaged by German racing driver Michael Schumacher, the Formula One world champion, who is to make a donation of $10 million.

WORLD LEADERS

As exhausted doctors, nurses, aid workers and troops continued their around-the-clock operations, world leaders began arriving in Asia ahead of a Jakarta conference on Thursday where the United Nations will launch a major aid appeal.

The toll continued to climb, with around 150,000 confirmed killed and millions left homeless or displaced.

The World Health Organization estimates there are more than 500,000 people injured and in need of medical care across six Asian nations. The United Nations estimates that 5 million people need some kind of aid and 1 million are homeless.

At least a third of those killed were children and there were fears that a "tsunami generation" of children was likely to suffer more than adults in the aftermath of the tragedy.

"We probably underestimated the impact on children," said UNICEF spokeswoman Wivina Belmonte. "Many people are already talking about the tsunami generation."

The main airport in Indonesia's Banda Aceh, a hub for relief flights, was closed to fixed-wing aircraft for much of Tuesday after a cargo plane hit a buffalo, the UN World Food Program reported.

In the devastated town of Meulaboh in Aceh province, effectively cut off for a week and with an estimated 40,000 feared dead, a damaged airstrip was cleared sufficiently for use by small Twin Otter aircraft, enabling medical teams to distribute bandages, dressings and painkillers.