Education is an export these days, earning more than $2 billion a year for the economy. Like tourism it does not send its product to consumers abroad, it brings the consumers here. That sort of export is particularly valuable because the consumers buy much more than the product marketed to them. Their living costs here also contribute to the economy.

Little wonder, therefore, that governments have been slow to act on persistent reports that question the standards and honesty of some of those providing export education in this country. The Weekend Herald reported that Massey University at Albany has stopped accepting students from several of the private language tuition centres that have proliferated in Auckland and elsewhere. It has found the students barely able to speak English and incapable of studying for a business degree.

Former staff of these "schools" tell disturbing tales of fraud. They say students can be given answers to test questions to ensure a pass and sometimes the centres sell pass marks to students who have failed at other schools. They call the centres "visa factories", providers of paper qualifications that help students gain permanent residency.

The students appear to know what is going on. Absenteeism is high. Many are said to be working and when they fail the course they are unconcerned. As one teacher told the Weekend Herald, "Within two or three hours they'd just go and purchase [a pass]. They'd tell me it cost them between $650 and $1000 and they'd just get it. There was nothing I could do."

Whistle-blowers have found the authorities slow to act. Successive governments have resolved to monitor the standard of export education more rigorously but these reports persist. Perhaps they take the view that the students are getting as much, or as little, English as they think they need, and since we are competing with other English-speaking countries for their custom, why make it harder for ourselves?

But that is a short-sighted view of the national interest. It is also unfair to those language schools that are doing an honest and conscientious job. They stand to suffer directly if New Zealand's reputation for export education is sullied. But the whole country and possibly its other exports stand to suffer in the long run if it becomes known as a place where education is corrupt and academic qualifications are unreliable.

New Zealand secondary schools have courses in English for non-native speakers. It is an established subject with its own examinations and standards. There is no reason that all private institutions could not be obliged to prepare students for the same exams. NCEA tests may be devised and marked within schools but results are checked with other schools in a way that would expose the frauds.

Immigration Minister Jonathan Coleman is considering steps to stop renewing visas for students who "hop" from one course to another that is similar. Immigration might also get power to deny visas to students who enrol with schools accused of breaking the rules. But we have heard proposals of this sort before.

Good international language schools have been complaining about the rogues in their industry for years. They say the typical response of the New Zealand Qualifications Authority has been to exact an undertaking from the rogues that things will improve. But nothing is done to hold them to it. An NZQA "quality assurance" official told the Weekend Herald it has now set up an 0800 line for anyone to report fraud. It will have to do better than that for non-English speakers who have come this far to make an educational investment.