Google, the world’s biggest search engine, is to ban advertisements for essay-writing services, amid claims that it is undermining the integrity of university degrees.

From next month, Google will no longer accept adverts from companies that sell thousands of essays and dissertations from as little as £70 to as much as £5,000 each around the world.

The essays, which are often written by freelance academics or graduates, and therefore harder to detect by plagiarism software, are frequently bought by overseas students and passed off as their own.

“I can confirm that we are changing our policy to disallow advertisements that promote the sale of academic paper-writing services,” a Google spokesman said. “Google is committed to maintaining high standards for the advertising we accept.”

Essay-writing companies reacted angrily to the move, but universities said that making life harder for the “essay mills” was a step in the right direction.

“Essay writing sites claim that students pay hundreds of pounds for model answers – but do not then submit these as their own work. We all know this claim is absurd,” said Drummond Bone, president of Universities UK, the umbrella group of vice-chancellors.

“We feel strongly about this because plagiarism devalues the efforts of students who work hard to achieve their degrees. It also damages the student who commits plagiarism, as they will not benefit from the research and learning experience.”

Universities UK members have severe penalties for those students caught cheating, with many institutions already using advanced antiplagiarism software to enforce this.

Essay-writing companies are a booming industry. Peter Taylor, of Coursework.info, the biggest online coursework library, claimed last year to have 240,000 registered users, a £400,000 turnover and to make £50,000 profit.

In an attempt to help universities cut down on student plagiarism, it added all of its essays to TurnitinUK, a plagiarism prevention database, which is used by most universities.

However, Matthew Wilson, managing director of Essaywriter.co.uk, said legitimate firms would suffer even though they warn students not to use such essays dishonestly.

With up to 80 per cent of his essaywriting customers coming through Google, he criticised the blanket ban on all services for writing and researching essays.

“We are very angry about this,” he said. “We are a legitimate company. We have got 3,500 researchers, tutors and lecturers and a big customer base.”

He said his customers ranged from parents whose children had problems with their coursework to overseas students, for whom English is their second language.

“They have often been doing exam-based work and so they struggle when they get handed theory-based essays and then fail,” he said. “They often feel they’re not getting the support they need and fall behind, going home after paying £10,000 a year, without any qualifications.”

Mr Wilson, a former English tutor, said his company’s tailor-made essays were intended to be used as a guide or tool for students, rather than to be passed off as original work.

His company, which also offers translation services, did not encourage plagiarism and copyrighted all the research that they sell.

Meanwhile, thousands of teenagers appear likely to defy government plans for compulsory education to 18, research suggests.

In March Alan Johnson, the Education Secretary, said that teenagers who dropped out of school or training at 16 would face criminal action and £50 fines if they refused to continue their education. He said he expected the sanctions, which may also include the confiscation of driving licences, to apply only to a small “hardcore” of refuseniks when the legislation is introduced in 2013.

But a report to be published today by the leading education charity CfBT, suggests that the view is “worryingly optimistic” and predicts that the threat of legal action will have to be applied to “large numbers of uncommitted young people”.

This could have disastrous effects on the education system, as resources would be diverted to enforcement. “The exercise of compulsion on a large scale makes the curriculum, monitoring, enforcement challenges significantly greater,” the report’s authors say.

Faced with a large-scale revolt, they question whether any government in 2013 would bother trying to force reluctant teenagers to study.

The findings will come as a blow to the Government, which has presented raising the education leaving age as a vital policy.