Welsh language campaigners have called for public funding of the National Botanic Garden to be suspended after signs advertising the attraction were installed on the M4 only in English.

Cymdeithas yr Iaith claimed the Garden, at Llanarthne, was “bordering on arrogant” and “in breach of its language duties” following the recent erection of the road signs.

The society also criticised a lack of Welsh-language services at the Garden and, in letters to First Minister Carwyn Jones and Kevin Madge, leader of Carmarthenshire County Council called for public support to be withheld.

Cymdeithas yr Iaith Gymraeg wrote: "The Garden's attitude towards the Welsh language is very far from what is expected in the 21st century.

“We call on you to hold the funding back until the Garden shows due respect to the Welsh language.”

Manon Elin, on behalf of Cymdeithas yr Iaith, said: “Why should people fund the National Botanic Garden of Wales when it is so disrespectful towards the Welsh language? “

National Botanic Garden Director, Dr Rosie Plummer, said: “The Garden, as an iconic organisation and environmental flagship for Wales, is very committed to its wide support for the culture, language, and heritage of Wales and makes substantial allocation of resources and effort to this.

“It is therefore enormously disappointing to be subject to such vigorous approaches that largely seem to overlook the very wide range of ways in which the Garden actively contributes to bringing the unique importance of Wales to everyone who visits.

"The Garden works hard to promote and develop its language resources to the more than two million visitors it has welcomed in just 15 years.

“All our press releases, brochures, published materials, and visitor signage is bilingual and we take a great pride in the way in which we present our information and learning, and encourage use of the language in a friendly and engaging way.

"The Garden hosts many thousands of education visits each year, and offers more than 50 curriculum-linked courses through the medium of Welsh.

“We are very sorry indeed that the matter of a single, targeted marketing banner has been felt, in any way, to diminish our commitment or our representation of the importance and essence of the Welsh Language.”

She added that the Garden was “fully committed to its Welsh Language Policy”.