The report found that, overall, voluntary income for the top 500 charities is continuing to grow, increasing by 4.8% to £5.3 billion.

Cancer Research UK has maintained its position as the top fundraising charity with a voluntary income of £344 million. The charity earns £167 million more than Oxfam, which is in second place. The National Trust, British Heart Foundation and RNLI are also in the top five.

But while the biggest names in the third sector are doing well, small and medium sized charities are struggling to maintain their position. Charities placed in the bottom 100 of the table have suffered the greatest loss of income at minus 12%.

“The growing gap between large and small charities is very worrying for the smaller causes,” said Cathy Pharoah, director of research for Charities Aid Foundation and co-author of the report. “Small to medium sized charities are going to have to get smarter and look at collaboration over marketing and fundraising with others if they are going to compete with big brand name charities.

“While there is a perception that the public hold local and specialist charities in high esteem, this isn’t translated into financial support. There is a real risk that we could lose the diversity of the sector unless smaller charities rise to the challenge,” Pharoah warned.

Donations from individuals, companies and trusts to the top 500 charities have now reached £3 billion, and income from legacies also totals over £1 billion. The biggest growth comes from fundraising events, a 15.6% increase to £418 million.

Religious international causes have increased their aggregate voluntary income by 49% - the largest increase of any cause - taking over disability causes. Education, training and research causes suffered the most with a fall of 31%, followed by youth causes with a fall of 22.4%.

The unprecedented level of disaster appeals in 2004/05 led to a significant rise in the amount of money given to international causes, with a total of £60 million donated in just one week after the tsunami.