RESCUERS were last night battling against the clock to save two men believed to be trapped beneath the rubble of a Glasgow factory.

Four women and three men died in the explosion at Stockline Plastics in the Maryhill area of the city.

But Strathclyde Assistant Firemaster Bill McDonagh said there remained a "very good chance" of finding someone alive in the rubble.

Mr McDonagh said rescuers had been calling the mobile phones of the men still trapped in the rubble in a bid to find them but the crew could not hear any response.

Speaking at the scene, he said the rescue operation took a "fundamental shift" just before 9pm. He said: "We have tunnelled in as far as we can go and it's becoming very dangerous now because some of the rubble is starting to slip underneath and we are in the basement area.

"The contractors are going to cut the roof into four sections and move the sections so we can start to tunnel under the debris.

"We are still looking for two persons and it's imperative that we get in there as quickly as we can to get them out, we want this roof off as quickly as we can. We will continue for as long as it takes.

Mr McDonagh added: "If we don't take off the roof the building, which is very unstable, could fall on top of our firefighters.

"As soon as the roof is off we can get all of our search and rescue teams in there.

"It's a fight against time now. We have to get in as fast as we can and give every chance possible to the people who are still in there. "

He said that while digging, rescuers had found several air pockets within the rubble.

On the chances of finding anyone alive, Mr McDonagh said: "In some places people have been found six, seven days after a collapse.

"The temperature has been very kind to us. We have not had any rain and it has been very warm and fairly reasonable so I think there is a very good chance that we could find someone alive in there."

More than 80 firefighters were still involved in the rescue operation last night.

They included search and rescue specialists from across the North-East.

The North-East teams, who are trained in urban search and rescue, included Dave Earle, of Cleveland Fire Brigade, an officer from County Durham and Darlington, plus others from Northumberland and Tyne and Wear.

The two teams each contain ten specially-trained firefighters.

The four-storey building was flattened in seconds following the blast shortly after midday on Tuesday.

Scotland's First Minister Jack McConnell visited the site and pledged a "full and thorough investigation".

Inspectors from the Health and Safety Executive were last night still awaiting the go-ahead from emergency services to proceed with on-site inspections.

Survivors have suggested four ovens in the factory - two electric and two gas - may have exploded.

As the people of Glasgow began to come to terms with the enormity of the tragedy, police issued the names of the seven victims.

Among them was Stockline Plastics' chief executive Stewart McColl, 60, who was believed to have been on the fourth floor at the time of the blast.

The other victims were: Ann Trench, 34, of Glasgow; Margaret Brownlie, 49, of Strathaven, Lanarkshire; Tracey McErlane, 27, of Glasgow; Peter Ferguson, 52, of Kilbarchan, Renfrewshire; Annette Rosina Doyle, 24, of Glasgow; and Thomas McAulay, 41, of Glasgow.

Chief Superintendent David Christie confirmed 44 people were taken to hospital after the blast. Sixteen remained in a serious condition.