One in five charities has seen a drop in income averaging 30 per cent over the last month, according to an Institute of Fundraising survey.
Of the 293 charities that responded, 40 per cent said that their last month's income had been dramatically affected, either positively or negatively.
Some 18 per cent reported an income rise averaging 40 per cent.
Almost 70 per cent of those who had seen their revenues rise or fall attributed the change to the tsunami appeal. Around a third said it was too early to tell if their income had been affected by the tsunami, but 54 per cent of these thought there would be a negative impact on their fundraising income over the year.
Of the 56 per cent that ventured a longer-term prediction, just over half thought the tsunami would have a positive effect on their fundraising, while 45 per cent foresaw a negative impact.