Ineos has promised a full investigation into the cause of a gas leak in the Kinneil Gas plant at its Grangemouth complex in Scotland, on May 2. The leak in a pipeline transporting gaseous ethylene occurred around noon. No casualties were reported.

Reports said pupils at schools in the area were kept indoors as at the request of police. Members of the public were advised to stay inside, with the south side of the plant evacuated and local roads temporarily closed.

The chemical group said its staff were evacuated from the danger zone, emergency procedures implemented and its incident management team mobilized. It said the leak was contained to the immediate vicinity of the affected plant and that other areas within the Grangemouth complex, including the adjacent refinery, unaffected by the incident.

In response to the incident, the UK trade union Unite, which has been at loggerheads with Ineos management not least since a 2013 strike at Grangemouth led the company to threaten to close the site, called the leak “concerning” and said it has requested an “urgent meeting” to ascertain the cause.

Unite’s Scottish secretary, Pat Rafferty, urged Ineos managers “to accept that cooperation is the best policy when it comes to ensuring that Grangemouth stays safe,” and drop its “damaging and needless effort to break the union.”