Somali pupils must go back to their roots and learn their mother tongue to end a downward spiral of low achievement, according to the head of Cardiff's ethnic-minority achievement service.
Geraint Evans said that latest research proved Somali pupils who had a good grasp of their native language did better at school.
He called for young Somalis to have more access to lessons in their own language, in and out of school. And he said GCSE Somali should be introduced to encourage fluency among pupils who currently see learning their own language as a "waste of time".
Cardiff's Somali community is the oldest ethnic minority in Britain, but the mother tongue is gradually dying out as English becomes the first language.
At a conference on Somali achievement and language training held in the city, Mr Evans said this was now known to be a key factor in underachievement.
He told delegates: "In Cardiff, Somali pupils are doing worse than other ethnic minorities and we must look at why this is so, and how we can raise standards."
There are 875 Somali pupils in Cardiff - 353 in primary schools and 533 in secondary education. Figures for the city reveal a drop in the performance of Somali pupils in 2004 compared to 2003. A fifth achieved five GCSE passes at grades A*-C, down 7 percentage points from 28 per cent in 2003.
The comparative study, which found that Somalis are the lowest-performing ethnic-minority group in the city, included Pakistani, Bengali and white pupils.
In 2004, half of Cardiff's white pupils achieved five good GCSE passes, compared to 36 per cent of their ethnic-minority classmates. A third of Bangladeshi children reached the same standard, compared to 47 per cent of Pakistani pupils.
The ethnic-minority achievement service teachers presently cover 42 schools in the Cardiff area. Mr Evans said heads, mainstream teachers and ethnic-minority pupils needed to work more closely to stem the decline in performance.
He said: "We are making huge moves forward, but there still needs to be more teamwork from schools and agencies to help raise educational achievement in the Somali community. This is happening more in Cardiff, Swansea and Newport than in rural areas, but there is still a long way to go."
New initiatives, such as the Somali Parents' Forum, are helping to pull parents on side. Earlier this year, more than 100 parents from Cardiff's Somali community gathered in the Butetown area to find out how they could help their children achieve better results. The meeting was organised by Asha Ali, a teacher at Cardiff's Fitzalan high school.
She said: "Somali parents from all tribal and religious backgrounds attended and they all had one common aim - to find out how they can help raise the educational standards of their children.
"There was such a huge will to change things in the community and I was so proud to be part of it."
Ms Ali runs a Sunday homework club for Somali children - "the pupils are keen to work hard to improve" - and Fitzalan offers out-of-hours language courses. But she believes the key to reviving the language is having a GCSE course.
"It is crucial that Somali is offered at GCSE, otherwise pupils don't see any point in learning it. The age-old argument is there is no demand for the exam, but if we don't try, how do we know?"