The public inquiry into the ICL Plastics disaster heard yesterday that health and safety officials failed to carry out follow-up inspections or spot well-known hazards at the factory and did not enforce their own orders.

It also emerged yesterday that the company ignored an instruction to install a sprinkler system above a tank containing liquid petroleum gas and defied a ban on using a basement, where the gas built up, as a work space.

A prohibition notice was sent from HM Inspector of Factories in 1976, informing Stockline Plastics, part of the wider group of related companies operating from the Glasgow site, that using the underground room was dangerous.

It stated the use of the basement as a storeroom or workroom will involve serious risk of serious personal injury but for years afterwards a basement at the factory in Maryhill was used by the firm's two builders as their base and store for materials and tools.

Inquiry Counsel Roy Martin asked Alistair Keddie, Health and Safety Executive principal inspector, who visited the factory in 1988, if he was aware of the notice. He replied: "Not until I was shown it recently."

The company was also informed, following a visit by a Health and Safety Executive inspector in 1982, that it should install a water spray system above the LPG tank as a cooling measure.

The public inquiry is being held into the circumstances of the explosion at the ICL Plastics factory in Glasgow in May 2004.

Nine people were killed and more than 30 injured when a build-up of liquid petroleum gas in the basement area exploded, causing the building to collapse.

In December 1982, a letter was sent from ICL to the HSE stating the materials were in the factory and the work would be done over Christmas.

However, the safety measure was never put in place. The inquiry was shown a memo from ICL owner Campbell Downie six years later to his then managing director, a Mr Stott.

It said: "I resist the notion a drench system should be installed. We do not have a sufficient water supply and the cost would be enormous."

A handwritten note on the typed memo added "We must try to talk them out of the drench but that's difficult this time round."

Lord Gill, who is chairman of the inquiry, said: "It seems there was a desire of ICL to stall on the implementation of the requirements."

The inquiry was also told how an inspector discovered visits to check recommendations regarding the LPG tank, requested in 1982, were not followed up six years later.

Mr Keddie said although he has no recollection, records show he was passed the ICL file in 1988 and was preparing for a visit when he checked back on the case history.

The inquiry continues.