The head of the body that lists and promotes Scotland's historic buildings and monuments has said any attempt to merge it with another organisation will be resisted.

Diana Murray was speaking at the launch of an exhibition marking the centenary of the Royal Commission on the Ancient and Historical Monuments of Scotland (RCAHMS).

The exhibition, which opens tomorrow at the City Art Centre in Edinburgh, comes as RCAHMS prepares to fend off moves to amalgamate the commission with Historic Scotland and/or the National Archives as part of government plans to reduce numbers of arms-length public bodies.

Diana Murray, head of RCAHMS, said the body would resist a merger and maintain independently its collection, said to be of "huge national importance".

She said yesterday: "We are concerned about the uncertainty of not knowing what's going to happen to us.

"We have been an independent body for 100 years and that has worked very well. We have been under review under a series of governments for 20 years and they have always come out with the view that it's most cost-effective and it is better for Scotland to have an independent body.

"Losing us as an independent organisation is certainly high on their (the government's) agenda and my view on that is if they are really serious about this then what needs to be done is create a new organisation that is actually distinctive and valuable for Scotland rather than get us subsumed into somebody else's agenda, either Historic Scotland or the National Archives, because we don't really fit with either of them.

"That might be a better way forward but of course again that would cost money."

The Royal Commission is responsible for recording, interpreting and collecting information about the built environment. This information, which relates to buildings, sites, and ancient monuments of archaeological, architectural and historical interest is made freely available to the public.

It has a staff of around 100, charitable status and a collection of 14 million items.

Glasgow University archaeology expert Tony Pollard described RCAHMS's work as vital, adding that it is the "primary organisation for recording and surveying all historical sites; the stopping-off place for all archaeology".

The free exhibition, Treasured Places, comprises more than 180 fascinating drawings and photographs.

Highlights include aerial photographs of Woden Law, an iron-age hill fort revealed through the light of a winter sun and a dusting of snow.

A spokesman for the Scottish Government said yesterday: "We intend to streamline delivery of public services around historic archives and to clarify the roles of organisations operating in the historic built environment sector.

"We will therefore be looking in detail at ways in which we can better align the activities and service delivery of RCAHMS, the National Archives of Scotland and Historic Scotland in these areas."