Demolition of parts of a former electronics factory has been halted following concern about the possible release of potentially hazardous materials.

The Scottish Environment Protection Agency (SEPA) has ordered contractors to stop work on sections of the former Chunghwa picture tubes plant in Lanarkshire because it believes they contain ozone-depleting substances.

It is understood SEPA officials are investigating reports that cladding and roof panels from the television tube factory have been stripped and crushed on site, which would have released the chemicals.

SEPA believes the building parts contain hydrochlorofluorocarbons (HCFCs) - refrigerants which are harmful to the ozone layer in the atmosphere, and crushing the panels in the open air could release HCFCs.

The agency said the panels should be taken to a specialist processing plant.

Officials are still checking whether the HCFCs in the building were used in insulating foam, or are in the more harmful liquid form, which can cause light-headedness, headaches and skin irritation.

The agency is also investigating whether any potentially-hazardous material has already been removed from the site of the plant, at the Eurocentral business park near Mossend.

The factory, which manufactured cathode-ray tubes for televisions and other screens, opened in 1996 and closed five years ago. Officials ordered demolition to be stopped on Monday last week and visited the site the following day.

A SEPA spokeswoman confirmed that it was "investigating activities being undertaken" at the plant and said: "Until further information is provided by the company involved, SEPA has advised that the demolition of certain sections of the buildings stop. We have not asked for all work at the site to stop.

"The sections in question are Kingspan panels, which SEPA believes contain ozone-depleting substances."

The spokeswoman said the investigations would include the type of wastes being generated at the site, the destination of any wastes that had left the site, and any waste that remained on the site.

She said: "If they are large panels with metal struts, they should be broken into large chunks, which would result in less chance of HCFCs being released , and the chunks should then be sent to the processing plant.

"While our vigilance means this hazardous waste should now be dealt with properly, SEPA would remind all contractors that waste from any planned demolition must be disposed of legally."

SEPA said Morton Demolition was the contractor involved, with the project being managed by Bowmair & Kirkland.

A spokesman for Eurocentral, which is overall charge of developing the site, said contractors Bowmair and Kirkland were working closely with SEPA on the issue.

He added: "The demolition is going ahead and is on schedule, to be completed next month."

Ed Dearnley, a policy officer at campaigning group Environmental Protection UK, said SEPA had to act to keep the country in line with tough laws on the release of HCFCs.

The 670-acre Eurocentral site is being redeveloped in a