Corus is to sell its Teesside coil plate mill to China as part of a multi-million pound deal.
The mill, which has been closed for two years, is to be dismantled and shipped out to the Far East.
Bosses of the Anglo-Dutch company are yet to reveal who they are selling it to but said it was not a direct competitor.
The deal kills off hopes of the plate mill ever reopening.
About 230 people lost their jobs when the mill closed - marking the end of integrated steel-making on Teesside.
Redcar MP Vera Baird said: "The site would never have reopened under Corus, so it is good they are making some money by getting rid of a dead asset.
"There is a chance that Teesside could end up supplying China. If we work hard this could be Teesside's new export customer."
Work to dismantle the mill is due to start next month and, according to an independent analyst, Corus has cut off a vital lifeline which could have saved thousands of jobs. The sale is part of a wider move by the firm eventually to offload Teesside operations or close them down, according to the analyst.
Peter Dupont has assessed Corus Teesside's potential for success under radical new plans which will see it stand alone as a merchant mill.
Mr Dupont: "In my view, Corus does not want to operate as a merchant mill. The likely alternatives are that it will be sold or closed."
The consultant was commissioned by the Tees Valley Development Company and Redcar and Cleveland Borough Council to produce a report on the chances of steel making surviving on Teesside.
In the confidential document, Mr Dupont states: "The economics of the proposed Teesside merchant mill could be considerably enhanced by resuming hot-strip production at the site."
The report points out that the coil plate mill could be relatively cheaply resurrected and could produce 1.6 million tonnes of hot-strip metal a year.
That would provide an immediate use for some of the proposed 3.5 million tonnes of slabs and blooms expected to be sold on the international open market.
The report adds: "Hot-rolled coil offers the potential for slightly higher margins than pure semis business."
Mr Dupont predicted that there was a 30 million-tonne market in Western Europe for hot-rolled coils which the merchant mill could take advantage of.
David Walsh, member of the Steel Taskforce and One NorthEast board member, said: "Obviously the deed is now done. It is a pity Corus did not see fit to talk to the representatives of regeneration agencies and the taskforce.
"We could probably have had a very good discussion about the merits of this move."
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