Steel giant Tata has announced that production has restarted at the second blast furnace at its Port Talbot site.
The project - which cost £185m - began after Blast Furnace No.4 was decommissioned in July 2012.
A Tata spokesperson said the work has made the furnace "more efficient", along with upgrading its capacity and environmental performance.
In November, Tata announced it would make 584 of its workers in Wales redundant, blaming high energy costs and a fall in global demand for steel.
Business Secretary Vince Cable has admitted that UK Government help for steelmakers with operations in Wales such as Tata and Celsa has been 'slow in coming.'
But he blamed 'international rules' for slowing down efforts to aid companies struggling with high energy costs and global financial problems.
He told MPs on the Welsh Affairs committee that ministers recognise the difficulties facing steel companies and is working out ways of alleviating them. He was responding to a question from Labour MP Jessica Morden.
Representatives from Tata Steel will appear before the Welsh Affairs Committee later today.
Today's session is also expected to hear from the trade union Community and other representatives from the steel industry.
Traffic came to a standstill around Port Talbot this morning because of a protest by steelworkers.
Employees from the Tata plant were demonstrating after being told that they were to be replaced by cheaper labour from elsewhere in the EU.
Our Correspondent Richard Morgan reports from the picket line.
Contractors at Tata Steel's Port Talbot plant have had their jobs reinstated after holding an unofficial picketline this morning.
The workers had claimed they were being replaced by foreign workers on lower pay rates.
Following the protest, Tata Steel released a statement saying that discussions had taken place with the principal contractor. A spokesperson confirmed that the affected workers will now continue in their jobs until their parts in the project are completed.
A unofficial picket line is being staged at the Tata Steel plant in Port Talbot this morning after contract workers claim they were replaced by foreign workers on lower pay rates.
It comes a day after 47 contract workers were told their work was coming to an end.
The men claim they have now been replaced by Polish and German workers on lower pay.
Tata Steel say they have not made any employee redundant and a single contract that was been carried out by a German company has now come to an end.
One contract worker - Robert Newton - says he was working at the plant as an insulation engineer for three months and was told the news on Monday when the men turned up after the holidays.
The men, who say they are all members of the GMB union, say they will demonstrate at the plant all morning.
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A spokesperson for Tata Steel in Port Talbot says the company is co-operating fully with an investigation by the South Wales Police and the Health and Safety Executive.
We can confirm that an incident took place yesterday afternoon. One person was affected and taken to hospital. We are co-operating fully with the investigation.
Mr Dangerfield added that he could not comment on the circumstances of the incident due to the investigation.
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