The GMB union said several thousand of its members at the company will vote in the next few weeks on whether to launch a campaign of industrial action.

The union's executive decided to press ahead with the ballot as the mothballing started at the plant in Redcar with the loss of up to 1,600 jobs.

The move signals the end of a proud chapter of industrial history as the last steel-making furnace on Teesside is turned off after working continuously for 150 years.

Keith Hazlewood, national officer of the GMB, accused Corus of going back on a promise to delay the mothballing of the plant.

"The decision to mothball the plant suggests that Corus did not really want to keep it open or sell it to another steel company.

"The decision is bad for Britain and for our manufacturing industry and our members will now be asked to respond."

Tata, the Indian firm that owns the site, insists it is seeking a buyer and the works are only being partially shut down.

But no-one knows whether the massive furnace will ever be lit again.

At a news conference after meeting Corus management on Thursday, Business Secretary Lord Mandelson wagged his finger at journalists who repeatedly asked if it was a tragic day for Teesside.

"It is not yet a tragedy because it is not closing," he said.

"It is a strong message to say to other potential investors that this is not a closure of the plant."

Corus says it has lost £150m running the furnace since customers pulled out last year, and blames them for the mothballing.

But retired welder George Duffield, a steelworker from the age of 15, felt poor management was at fault.

"They've just said we don't need that, you can go," he said.

"The lads in here, some of them have been there 25 years. What are they going to do?"

Mothballing the giant furnace will be a slow process, spread over more than two days.

The last of the raw materials was fed in yesterday, and as the molten steel is let out at the bottom, the top of the furnace will empty and be gradually cooled.

As the material drops down, the massive pipes forcing superheated air into the furnace are expected to be turned off at around midnight.