The cause of a Glasgow factory explosion which killed nine workers was revealed today ahead of a court trial.

The operators of the Stockline plastics factory in Glasgow are accused of health and safety failures in relation to the 2004 blast.

Five men and four women died and 40 others were injured in the explosion in the Maryhill area of the city.

Prosecutors said today that evidence relating to the deaths and the cause of the blast have been agreed with the defence ahead of next month's trial of ICL Plastics Ltd and ICL Tech Ltd.

At a hearing at the High Court in Glasgow advocate-depute Angus Stewart QC told judge Lord Hardie the explosion was "caused by the ignition of petroleum gas from a pipeline".

The trial is scheduled to begin on August 13 and is expected to last about 12 days.

Lord Hardie told victims and their family members in court today that discussions between the Crown and the defence was normal in the run up to trial and served to minimise the leading of evidence that was not in dispute.

The factory operators are being prosecuted under the 1974 Health and Safety Act.