More than a third of charities blame 11 September for reducing their income, the annual charity survey from law firm Charles Russell has found.
In total, 19 per cent said the terrorist attacks had caused a "significant decrease" in their funds, while 17 per cent said they had suffered "some decrease".
The survey, which will be unveiled today at Charles Russell's charity conference, covered 100 charities, split evenly between those with income under £1 million, between £1 million and £10 million and those over £10 million. Interviews were conducted with finance directors or equivalents.
According to the survey, 28 per cent of respondents blamed the terrorist attacks for the reduction in the value of investments. A further quarter said the fall in the number of tourists had led to a fall, while 19 per cent mentioned hikes in insurance premiums.
The downturn in the stock market over the past year was cited by 61 per cent of charities as having a negative impact on their finances. Just over a third of respondents said their investment portfolio had diminished in value. Predictably, larger charities have been the hardest hit, with 83 per cent of charities with income above £10 million saying the decline had been "significant".
Kevin Sims, director of market research company the Charity Fund Partnership, which is conducting its own research into the charity investment market, said that the survey provided a warning about the sustainability of some charity activity. "One of the largest professionally managed UK pension schemes (USS) has recently announced a 24 per cent reduction in the value of its investments over the past seven months. If, as seems likely, anything approaching this scale of decrease has been witnessed by charities then it could have serious consequences on their ability to work to the same extent as before," he said.
The survey also gives some indication as to the size of the "dent" in charitable assets. In last year's survey, 24 per cent of charities had less than £2 million in funds. This has grown to 39 per cent this year.
While income from investments has fallen, the area remains the most popular source of core funding with 85 per cent of the bigger charities using it.