A gas technician who inspected a tank at a factory which later exploded, killing nine workers, said he was "never really happy" with it, an inquiry heard today.

Concerns were raised over the site of a gas container on day two of the investigation into the ICL plastics factory disaster in May 2004.

Operators ICL Plastics and ICL Tech were fined £400,000 after admitting health and safety breaches last year.

The inquiry heard today that a technical manager with Calor Gas, Alexander Clezy, who is now dead, visited ICL after a company driver complained about the state of the site.

He said in a police statement: "It (the tank) was too close to the wall at the back of the tank.

"The tank had been so close to the wall that Calor couldn't paint the back of the tank when they were maintaining it."

Mr Clezy said in a second statement: "I noticed that the ground had been raised because there was now a channel round the tank not allowing free flow of gas in the event of a leak."

He added: "I was never really happy with the site because it had built LPG (liquid petroleum gas) storage within a built-up area."

It was not clear from the statement in what year Mr Clezy visited the factory.

A total of 56 people were caught up in the blast at the former textile mill, with nine killed and more than 30 seriously injured.

Glasgow High Court heard last year that the tragedy was caused by a build-up of LPG which leaked out of pipework installed in 1969.

The pipework was initially installed above ground but had been buried with the raising of the yard years later.

The public inquiry chaired by Lord Gill was launched to investigate the circumstances and prevent another disaster from happening.

Today it heard from workers with Calor Gas who supplied ICL with gas until shortly before the disaster.

It emerged that, in a letter dated September 8, 1988, health and safety bosses recommended that part of the pipework carrying LPG vapour into the factory be excavated for a check.

ICL called in Calor, whose safety inspector wrote a response to the Health and Safety Executive dated January 4, 1989.

The letter addressed several recommendations such as pressure tests but did not appear to make reference to the excavation work.

Inquiry chairman Lord Gill said: "What is clear is that one thing the letter is not saying is that we will see that the underground pipework is excavated."

Safety inspector Maurice Coville, appearing in person at the inquiry, said the advice had come from technical manager Mr Clezy.

Lord Gill asked Mr Coville: "Presumably the examination of the riser pipe (a vertical pipe) wouldn't necessarily tell you anything about the condition of the pipe that was buried?"

Mr Coville said: "Not in itself. But depending on what they saw there they might have gone deeper."

Lord Gill went on: "If you had a pipe that was on the brink of failure, but had not yet corroded, it would pass a pressure test?"

The retired inspector replied: "Yes."

The inquiry has yet to hear whether the recommended excavation was carried out at that time.

Another witness, retired gas engineer Keith Young, said he could not think of any incidents where corrosion-protected pipework had failed.

"I'm not aware of any shelf-life being specified anywhere," he said.

The first phase of the inquiry at the Community Central Hall in Maryhill is expected to last more than three weeks.