By Bill Wilson BBC News business reporter

Critics say rock stars should be careful about what they say

With an ever growing army of celebrities getting involved in efforts to raise awareness of poverty in Africa, some have hit out against campaigns which they say are "high on celebrity octane" but low on political substance.

Critics say Bob Geldof's Live 8 concerts make up for a somewhat unsavoury gathering of "white millionaire pop stars saving Africa's helpless".

Consequently, factors that cause poverty, such as politics and trade, are lost in musical hype, they say, and this leads people to believe a continent's woes can be tackled by buying a wristband or a T-shirt.

'Message across'

Businesswoman Charlotte di Vita, 37, founder of the Trade Plus Aid charity which provides food, medicine, housing and education to people in poor countries, believes the protestors are missing the point.

Contributing artists include: Ewan McGregor Sir Paul McCartney Samuel L Jackson Nicole Kidman Snoop Dogg Sir Richard Branson George Clooney Jerry Hall

"There is niggling from some observers about using famous people, but if you asked a starving child in Sudan whether they preferred something to be done - by whatever means - or nothing at all, there would only be one answer," she says, insisting the celebrity route is legitimate.

Ms di Vita's latest project, 21st Century Leaders, has enrolled the help of more than 200 celebrities both to raise awareness and promote a range of issues around the world, as well as to raise money for a variety of charities.

Ms di Vita plans to sell limited edition plates, cups, wristbands and t-shirts that carry the artwork famous names from the world of music, film and fashion, as well as royalty, sports people, business people and world leaders.

"The reason we chose this method was precisely because they are well-known and could get the message across to people who might otherwise not be in touch with important issues," insists Ms Di Vita who has previously created designs to raise money for fair trade projects.

"If I can raise $325,000 a year for charities from my designs for teapots, then if you put a famous person on the side you could be raising millions".

Damaging the cause

In general, critics of celebrity endorsement have no gripes with projects like Ms di Vita's - projects that encourage people to get involved and open their wallets to support good causes.

Mr Monbiot is wary about celebrities endorsing politicians

At a higher level, though, some feel famous people's involvement can do more harm than good by lending legitimacy to politics that, at best, falls short of making a real difference, while at the same time cementing a belief among ordinary people that the problems are being solved.

Two artists in particular are finding themselves in the firing line after having praised the recent decision by G8 leaders of the world's richest nations to write off the debts of 18 countries.

The debt relief package and its architects were hailed by the rock artists Mr Geldof, who saw it as "a victory for the millions of people in the campaigns around the world", and Bono, who described it as "a little piece of history".

But despite their" obvious commitment to poverty reduction", the rock stars' efforts to "reach powerful people through flattery" could backfire, argues anti-poverty campaigner George Monbiot.

Mr Monbiot is angered by the conditions imposed on poor countries whose debts are written off; conditions which he sees as an "extension of Western power and influence" that is part of the problem facing Africa.

"The conditions on indebted countries are in many ways as bad as the debts are," he says.

"Geldof and Bono are in danger of turning a well thought out campaign for full and unconditional debt relief into a philanthropic campaign," Mr Monbiot says, insisting that the two are not qualified to determine whether or not world leaders should be congratulated or condemned for the debt relief package they have put together.

Political justice

But supporters of Mr Geldof and Bono are largely dismissive of such criticism, however, insisting that much has been done since 1985 when Geldof and his friend Midge Ure organised the Live Aid concert that raised �40m for famine relief in Africa.

Ms di Vita applauds celebrities who get involved

"Geldof, Bono, and other well known figures are taking on responsibility where others, who should, are not," insists Ms di Vita.

Indeed, with the Live 8 concert being organised simultaneously in five cities on 2 July, Mr Geldof declares that this time it is "not for charity but for political justice".