The National Trust has defended its decision to include references to creationist theory at a new state-of-the-art visitors' centre at the Giant's Causeway in Northern Ireland.

The move was hailed by a Christian group which said the gesture "both respects and acknowledges an alternative viewpoint" on the origins of the earth.

But after facing criticism for including theories that the planet is only 6,000 years old, the Trust said it had merely acknowledged the presence of such views and was committed to scientific evidence on the origins of the Causeway.

The issue of including creationist theories has sparked controversy in the past in Northern Ireland, when prominent members of the Democratic Unionist Party at Stormont lobbied for museums to include such opinions.

The Causeway is a Unesco World Heritage Site and features more than 40,000 interlocking basalt columns formed millions of years ago by volcanic activity.

The Trust said the new £18.5 million centre, opened by First Minister Peter Robinson and Deputy First Minister Martin McGuinness on Tuesday, showcased the science and the stories of the Giant's Causeway.

A National Trust spokesman said: "The interpretation in the visitor centre showcases the science of how the stones were formed, the history of this special place and the stories of local characters.

"We reflect, in a small part of the exhibition, that the Causeway played a role in the historic debate about the formation of the earth, and that for some people this debate continues today.

"The National Trust fully supports the scientific explanation for the creation of the stones 60 million years ago.

"We would encourage people to come along, view the interpretation and judge for themselves."

The interactive exhibition in question includes an audio package re-enacting debates between historic figures, who argued over the origins of the Causeway, as well as their contrasting biblical and scientific beliefs on the origins of the planet.

The exchanges end with a further clip stating: "This debate continues today for some people, who have an understanding of the formation of the earth which is different from that of current mainstream science.

"Young Earth Creationists believe that the earth was created some 6,000 years ago. This is based on a specific interpretation of the Bible and in particular the account of creation in the book of Genesis.

"Some people around the world, and specifically here in Northern Ireland, share this perspective.

"Young Earth Creationists continue to debate questions about the age of the earth. As we have seen from the past, and understand today, perhaps the Giant's Causeway will continue to prompt awe and wonder, and arouse debate and challenging questions for as long as visitors come to see it."

Northern Ireland evangelical umbrella group, the Caleb Foundation, welcomed the inclusion.

In a statement, the Foundation's chairman, Wallace Thompson, said: "As an umbrella organisation which represents the interests of mainstream evangelical Christians in Northern Ireland, we have worked closely with the National Trust over many months with a view to ensuring that the new Causeway Visitor Centre includes an acknowledgement both of the legitimacy of the creationist position on the origins of the unique Causeway stones and of the ongoing debate around this.

"We are pleased that the National Trust worked positively with us and that this has now been included at the new Visitor Centre."

He added: "We fully accept the Trust's commitment to its position on how the Causeway was formed, but this new centre both respects and acknowledges an alternative viewpoint and the continuing debate, and that means it will be a welcoming and enriching experience for all who visit.

"This is, as far as we are aware, a first for the National Trust anywhere in the UK, and it sets a precedent for others to follow.

"We feel that it is important that the centre, which has been largely funded out of the public purse, should be inclusive and representative of the whole community, and we have therefore been engaged in detailed and constructive discussions with the Trust in order to secure the outcome we have today.

"We want to thank senior National Trust officials who have worked closely with us over a prolonged period, and we are pleased that this constructive engagement has helped to bring about such a positive result."