An initial post-mortem into the death of an agency demolition worker at Sonae’s chipboard plant on Saturday proved inconclusive.

Merseyside police said further tests would now be carried out as to how James Dennis Kay, 62, died.

Initial reports said that the police and ambulance were called to the factory around 11am. Mr Kay was reported to have suffered serious injuries and died at the scene.

A joint investigation by the police and the Health & Safety Executive has been launched.

Mr Kay was working for Andrew Connolly Demolition on the site. A major fire at Sonae on June 9, involving 1,500 tonnes of woodchips, badly damaged its woodchip bunkers and the company had said these would need to be demolished. It is unclear whether Mr Kay was involved with this work.

Sonae Industria (UK) Ltd managing director Nigel Graham said that work at the Knowsley site was stopped on Saturday as a mark of respect following Mr Kay’s death, but would restart on today, August 8.

In mid-July, Sonae said that the demolition and rebuilding work would be mostly complete and output at Knowsley would be back up to 80% of capacity from October. But full capacity would not be achieved until the first quarter of 2012.

During the reconstruction period, Sonae has been supplying UK customers from its Continental mills. The latter have also supplied board for the value-added production lines at Knowsley, which have continued in operation.

Last year two maintenance subcontractors were killed at Knowsley, leading local MP George Howarth to repeat his call for it to be closed because of a number of accidents and pollution problems at the site.

Mr Graham said that Sonae was “totally committed” to the UK market and that reconstruction and modernisation work would improve Knowsley’s operational performance.