The research, conducted by charity comparison site Intelligent Giving, found that printed material such as newspapers and direct mail returned the least amount of donations per pound spent, at £2.99 and £5.08 respectively.

Other forms of communication fared much better, including telephone and online campaigns, with the most effective mechanisms being fundraising from trusts and major donors.

"Generally, people find direct mail is popular, but perhaps not as effective as many people thought," said a spokesperson at Intelligent Giving.

However, the study fails to take into account the scale or audiences of campaigns directed through the different media.

Direct mail and newspapers target a large base of people for whom charity giving is not a high priority, so campaigns targetting key individuals and organisations that are known for charitable work will offer better returns.

DMA director of media channel development Robert Keitch said of major donors and trusts, "there just aren't enough of them for the charity sector to rely on.   

And he added that direct marketing plays an important role in raising charities' profiles among potential donors of all types. "You have to ask, would major donors be as effective if their awareness of the charity was poor?," he said.

He said that while direct mail campaigns can often be improved upon in terms of effectiveness, it remains "a sophisticated intelligence-based method of communicating with an audience.

"It's an incredibly measurable source," he said.

Also see: Communisis warns of 'softened' demand for direct mail