25 March 2012 Last updated at 05:41 ET

'Blocked pipes' spark chemical alert at Edinburgh plant

A chemical alert at a pharmaceutical company in Edinburgh may have been sparked by blocked pipework, operators at the plant have said.

Emergency crews were called to reports of a small explosion at the Macfarlan Smith building shortly after midnight.

A spokeswoman for the firm, which makes painkillers, said it appeared pressure in the pipes had caused gaskets to blow. An inquiry is under way.

Nobody was injured and the firm said nothing harmful was released.

The building, on the city's Wheatfield Road, was evacuated and firefighters wearing chemical protection suits and breathing apparatus attended the scene.

The company's site director said the evacuation was standard procedure and a full root-cause analysis would be carried out.

Initial inquiries suggest a slug of material may have caused a pressure build-up in a piece of pipework, leading to an oxygen release through blown gaskets.

Macfarlan Smith, which is one of the world's oldest pharmaceutical companies, specialises in making opiate narcotics, such as morphine.