A Welsh language row has broken out on the Urdd Eisteddfod Maes - over the use of a foreign language in a performance.
Complaints have been made following the decision to strip Llanelli's Ysgol Dewi Sant of the top first prize in the under-12s choir competition.
The school won the contest at Margam Park, Port Talbot, singing a translation of Nkosi Sikelel' iAfrika (Lord Bless Africa)
- the former Africa National Congress anthem which has now been incorporated into the national anthem of South Africa.
Most of the song was performed in Welsh, but one verse was sung in the original Xhosa.
Competition rules state that as Welsh is the offical language of the event, only Welsh can be used on stage.
Once organisers had been alerted to the "rule-breaking" performance, they decided to remove the award.
They said the performance was able to slip through the net as this particular competition did not go through the usual network of local and county eisteddfodau.
But headteacher Meirion Davies criticised the decision - saying the school had used a foreign language when they won a similar competition five years ago.
"We were not aware of the ruling regarding other languages," Mr Davies said.
"In hindsight we should have checked."
But he added that the school had sent a copy of the piece it was planning to perform to the Urdd, so the festival organisers should also have checked its suitability.
Sian Eirian, director of Eisteddfod yr Urdd, said the organisers were sorry for the confusion caused because of the about-turn over the prize, and accepted full responsibility.
We have to accept that it is the Urdd's responsibility
Urdd chief executive Jim O'Rourke
But she said: "The Welsh language rule in the Eisteddfod clearly states that Welsh is the official language of the Eisteddfod, and that Welsh is the only language that should be used on the stage," she said.
"Therefore it is with great disappointment for the Eisteddfod that we will have to withhold the prize for the competion.
"My sympathies are totally with the children and their teachers... This situation should have become obvious in the prelims."
First prize was eventually awarded to Ysgol Llanddoged, form the Conwy Valley, and second prize to Ysgol Parc Y Tywyn, Porth Tywyn, Llanelli.
The event is expected to attract more than 100,000 visitors
Jim O'Rourke, chief executive of the Urdd, said the school had been, without doubt, "the best choir on the stage".
Urdd Chief Executive Jim O'Rourke said it might be possible in future years for some minority languages to be heard in eisteddfod competitions.
Earlier this year, a group Ysgol Penglais from Aberystwyth was removed from a county eisteddfod for using a verse in the Cornish language during their disco dancing.