If you want to make Celtic languages, including Welsh, appeal to young people then you need to give them a “cool” image, according to a leading academic.

The biggest danger to minority languages lies not in globalisation but in factors such as disputes over correct usage and an inability to adapt, according to David Crystal, honorary professor at Bangor university.

Speaking at the annual conference of the North American Association of Celtic Language Teachers (NAACLT), in Bangor, he highlighted how rock band the Manic Street Preachers used Welsh to advertise their new album in 1998 - even though they do not speak the language - because they were proud of their heritage.

But there was a negative reaction by some members of the Welsh establishment, who criticised the grammar of the wording.

Professor Crystal, a world-renowned linguistics expert, said: “This kind of confrontation does a language no good at all, especially one struggling to raise its profile among young people.

“If significant amounts of energy are devoted to quarrelling over which dialect is best, or condemning those who dare to experiment with it, valuable opportunities are lost. Small languages need prestige, and this is closely bound up with media support. Will another pop group repeat the experiment in Wales? I doubt it.”

Purist attitudes did not help the survival of small languages, he said. For anything to succeed with young people, it had to be “cool”.

This means having pop groups using the language in a way that youngsters can identify with; having their stories told and listened to; and using new technology to develop chatrooms and networks.

He added: “The internet is the best present the language diversity movement could have had, and one of the brightest prospects for revitalising the Celtic languages.”

The annual conference of the NAACLT takes place outside North America every five years, and was held in Bangor for the first time last week.

Another speaker told delegates that the ultimate goal should not be Celtic bilingual education just for the language’s sake but for “the social, cultural, economic, emotional and educational sake of our children”.

Bilingual education expert Professor Colin Baker, of Bangor university’s school of education, put forward 10 advantages of bilingualism, including ease of learning a third language, security in local and national identities, and tolerance of other cultures.

However, he pointed out that bilingual education was no guarantee of effective schooling. Minority-language use could stop at the school gates if education stressed language rather than people, or language development rather than child development.

“The notion of Celtic bilingual education has to be marketed so that parents, public and politicians believe in its value,” he said.

Dr Cen Williams, also of Bangor university, looked at the successful use of both English and Welsh in the classroom through “trans-languaging”, where teachers and pupils used both languages. He has been researching language immersion lessons for non-Welsh-speaking pupils who have moved to the area.

He concluded that there was more than one way to adopt two languages as media for education, and that teachers should not shy away from using two.

“The goal also needs to include improving teachers’ skills in trans-language teaching,” he said.