Growth in donated income among the top fundraising charities has slumped to just 0.5 per cent, a new report by the financial reporting firm Charity Financials says.
The report Top 100 Fundraisers Spotlight says that voluntary fundraised income was £5.9bn in 2017/18, although growth continued to slow in recent years.
Growth in fundraised income was between 4.5 per cent and 6 per cent between 2013 and 2016, according to the report, but fell to 2.8 per cent in 2016/17 and then to 0.5 per cent in 2017/18.
Overall income growth among the top 100 fundraising charities also fell, to 0.8 per cent, but income hit a total of £9.6bn in 2017/18, the report says.
The results echo recent findings by Third Sector in its study of the top 155 charities, which found that fundraising income had fallen from £5.1bn to £4.8bn, with legacy income rising from £1.5bn to £1.6bn.
According to the Charity Financials report, only 53 of the top 100 charities reported increases in total income, and the study says increasing fundraised income will be difficult in the future because of Brexit and constraints on public spending.
Forty-one charities in the top 100 fundraising charities reported falls in fundraised income, it says.
Legacies provided 25.8 per cent of all fundraised income at £1.5bn, according to the report.
The 100 charities in the list attracted a third of all charitable donations in the UK, with Cancer Research UK recording the highest level of donations at £443.2m.
The largest increase in fundraised income was at the Watch Tower Bible and Tract Society of Britain, which had an increase of £30m. The British Red Cross came second with a £20m increase, according to the report.
The report says: "The challenge looming over the future is to break through the apparent plateau in income growth, to regenerate public trust and the belief that giving to charities is a special, ethical and effective way of helping to address the social challenges which private and government sectors are not.
But it adds: "An encouraging fact looking forward is that, in a very challenging environment, income to the top 100 fundraising charities has been maintained after adjusting for inflation.
"It shows that charities have considerable resilience, that they can count on the loyal support of donors and that they have been fighting back."