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One of Britain’s leading charities has warned students not to take part in gap-year aid projects overseas which cost thousands of pounds and do nothing to help developing countries.

Voluntary Service Overseas (VSO) said that gap-year volunteering, highlighted by Princes William and Harry, has spawned a new industry in which students pay thousands of pounds for prepackaged schemes to teach English or help to build wells in developing countries with little evidence that it benefits local communities.

It said that “voluntourism” was often badly planned and spurious projects were springing up across Africa, Asia and Latin America to satisfy the demands of the students rather than the needs of locals. Young people would be better off simply travelling the world and enjoying themselves, it added.

Judith Brodie, the director of VSO UK, said: “While there are many good gap-year providers, we are increasingly concerned about the number of badly planned and supported schemes that are spurious - ultimately benefiting no one apart from the travel companies that organise them.”

VSO is drawing up a code of good practice to help gapyear students to find genuine voluntary work abroad.

The charity cited the case of a volunteer teacher in Africa who was surprised to be shunned by her fellow teachers, then discovered that her placement had led to a colleague being made redundant.

In another case, a volunteer in Mexico who thought that she would be working on a rural conservation project spent six months behind a desk in an office inputting data onto spreadsheets.

Another volunteer was asked to survey endangered coral reef in the Indian Ocean and dicovered that it had been surveyed countless times before by previous volunteers.

Taking a gap year used to be the preserve of only the wealthiest students, but it is now big business. Up to 200,000 people do it every year, including 130,000 school-leavers. The average gapyear traveller spends £4,800, and numerous companies have sprung up to get a slice of the market by offering prepackaged trips to projects for just two weeks at a time.

Gapyear.com, one of the biggest players, is offering places on dozens of voluntary projects, including work on a South African horse safari for £2,400 or two months observing coral and marine life in Borneo for £1,895. Another firm, i-to-i, is offering work with orphans in Argentina for £1,095.

In most cases the price does not cover the flight, but in-country travel, accommodation and an orientation session on arrival is included.

Ms Brodie urged students to go backpacking instead. “Young people want to make a difference, but they would be better off travelling and experiencing different cultures, rather than wasting time on projects that have no impact and can leave a big hole in their wallet,” she said.

Prince William went to Chile with Raleigh International in 2000 to help to build schools. The charity said that his work had sparked “a lot more interest” in its projects. Prince Harry worked with orphans in Lesotho.

Tom Griffiths, founder of gapyear.com, defended his business. “Some companies raise the expectations of students to unrealistic levels and make them think they will change the world. When they get there they discover they are only small players in the project and feel disappointed,” he said.

A spokeswoman for i-to-i defended its short-term voluntary breaks and said it made sure that all the projects were sustainable. “Not everyone has a year or two years to go off and do voluntary work,” she said.

Raleigh International backed VSO’s call for caution. “Students should be very careful about the voluntary work they choose,” a spokeswoman said.

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