Some UK charities have admitted they are struggling to spend the large sums of money donated to the tsunami appeal.
Aid agencies are working with people in affected countries on rebuilding projects
The British Red Cross says spending the money responsibly will be challenging and diverting funds may be a solution.
International director at the British Red Cross Matthias Schmale said around £20m of its funds could be diverted.
However, the Disaster Emergency Committee, the umbrella group of 12 aid agencies, said the £250m raised "can be spent", with £100m already allocated.
The Boxing Day tsunami claimed the lives of 280,000 people in 12 countries.
In an unprecedented response, the British public raised more than £250m for the appeal fund.
Mr Schmale told the BBC the challenge for the British Red Cross was spending its money beyond the three-year period, currently being envisaged by the relief effort.
"We have at our disposal about £60m at this moment, " he said.
"Out of which we have spent some £13m during the first six weeks of relief, bringing much needed items to the affected survivors of the tsunami."
"We think that within the next three years we can program up to £40m of the resources available to us for recovery and rehabilitation.
"And that begs the question of what we will do with the remaining £20m."
He said the Red Cross tended to be "most visible" in the first few weeks after a disaster, whereas other agencies may look at more mid to long term projects.
However, he felt the problem of spending the funds responsibly was one shared by all the charities involved.
"I think the distinctions between charities in terms of the work they are able to do post disaster are very little these days and show so we are jointly faced with the challenge of how to spend this responsibly," he said.
However, Mr Schmale added "it is still early days," and said the Red Cross with other charities, such as Oxfam and Save the Children, were just completing their assessments on the ground for mid and long term spending needs.
He added that aid efforts were hampered in area such as northern Sri Lanka and northern Indonesia where recent conflict had created security issues and damage to the infrastructure.
"It will take some time to clear the roads and make sure we can reach the people in need," he said.
The DEC, which co-ordinated the huge UK fund-raising effort, said all the money can be spent to help those affected by the disaster.
"The DEC can spend the money," said DEC spokesman Richard Bunting. "We have already allocated £100m for the first phase.
"That doesn't mean to say that there isn't any challenge.
"The scale of the devastation, the complexity of the situation and the need to provide long-term rehabilitation all make it challenging."
He said the DEC had initially set itself a three-year target to spend the money, but it was not "legally bound" by this.
Mr Bunting added if charities found they had too much money, it could be reallocated to others who needed more.
He said the DEC was not going to relocate money to the United Nations.
"The money will be spent wisely and well," he added. ""It is far too soon to be talking about 'too much money'."