Workers have told of the fear and anger sweeping steel communities across the country because of the wave of job losses which have heightened calls for urgent Government action.
Scores of workers lobbied MPs in Parliament ahead of an Opposition Day debate on the steel industry, during which Labour will press for immediate measures to prevent further job cuts.
Unions said a visit to Brussels by Business Secretary Sajid Javid was a "PR stunt".
Thousands of job cuts have been announced in recent weeks by Tata Steel and SSI in Redcar, Scunthorpe and Scotland, with cheap imports and high energy and emissions costs being blamed.
Further losses are threatened at steel processing giant Caparo Industries, which has gone into administration.
Workers wore T-shirts bearing the slogan Save Our Steel as they gathered in Westminster, saying they wanted to impress on ministers the urgency of the crisis.
The Unite and Community trade unions organised the lobby amid fears of fresh job cuts.
John Laurens, who has worked at the Scunthorpe plant for 35 years, said he believed there was still a chance the 1,200 jobs under threat at the Tata site could be saved.
"We just cannot let the steel industry die. This country wasn't built on banking, it was built on manufacturing.
"The steelworks at Scunthorpe is the lifeblood of the town. For every one person at the plant, another four are employed such as contractors, suppliers and shop workers.
"Losing so many jobs would have a massive impact on the area. We need action from the Government now, not warm words."
Kevin Cook, who has worked for 39 years at the SSI plant in Redcar, which is closing with the loss of more than 2,000 jobs, said workers were still "shell shocked" by recent events.
He revealed that workers with less than three years' service have only received two weeks of redundancy pay, capped at £475 a week.
"We are trying to sort out redundancy and pension arrangements but it is an absolute nightmare. Workers are feeling angry and shell shocked - some still don't seem to believe what has happened."
Jason Wyatt, an electrician at the giant Port Talbot works in South Wales, said there was apprehension in the area because of the state of the industry.
"There is a lot the Government can do immediately in terms of business rates and energy prices, which are the biggest hitters for our industry.
"We are worried about what the business will do in terms of any short-term measures such as lay-offs."
Agency staff have been told they are being laid off next month at Port Talbot, which has heightened fears about jobs.
"No one knows what is happening at the moment, but as far as we are concerned, the Government doesn't seem to be supporting manufacturing.
"The steel works is the biggest employer by a mile in Port Talbot and any job losses would have a massive impact on the area."
Andy Trigg, who works at Tata's steel tubes plant at Corby in Northamptonshire, said he was lobbying MPs to support workers losing or fearing for their jobs.
"Steel is a cyclical industry, with peaks and troughs. It is in a trough at the moment but hopefully it will pick up - but we need Government support.
"Energy and carbon costs are really hurting the industry, as well as cheap imports. Once the industry is lost, it is lost forever.
"Plants are closing that will never produce steel again. They are not like a tap you can turn on and off. If we had Government help to mothball plants, they could be brought back into life again.
"People are very worried."
Tony Pearson, who works on a separate part of the Redcar site to the SSI business, said the closure had created huge problems for the area.
"People are feeling very down at the moment and we need the Government to realise this is a foundation industry which should be saved."
The Business Secretary said he will tell officials in Brussels that urgent action across Europe is needed to tackle the crisis in the steel industry.
Mr Javid is calling for an emergency European Union meeting to discuss the state of the industry and unfair trade practices.
He was holding talks with trade commissioner Cecilia Malmstrom, internal market commissioner Elzbieta Bienkowska and vice-president Jyrki Katainen.
The Business Secretary said: "I want to see steel top of the EU agenda. We cannot stand by while the steel industry across Europe, not just in the UK, faces such unprecedented challenges.
"There are no straightforward solutions to the complex global challenges but the UK Government wants to work with the EU and our European partners to do all we can to support our steel industry."
Mr Javid has also been in negotiations with the commission on speeding up work to approve the UK's Energy Intensive Industries (EII) compensation scheme, which could benefit steelmakers.
David Hulse, national officer of the GMB union, said: "The Secretary of State is shameless in addressing the crisis in the UK steel industry with spin and PR stunts.
"The latest stunt of a trip to Brussels follows the Steel Summit talking shop. The complete lack of any action on dumping and energy prices, which can only be tackled by Government, has given rise to a wave of fear that even more jobs will be lost."
Shadow business secretary Angela Eagle said: "This Tory Government has sat on its hands whilst the industry has descended into crisis. They abandoned the people of Redcar, and it has taken thousands of job losses before they have even talked about action.
"The Business Secretary has shown no leadership in Europe and is only visiting after the Opposition has dragged him to this position.
"We have had weeks of talking, now we need action.
"The Government should stop hiding behind Europe when it comes to the Energy Intensive Industries compensation scheme, and should implement the scheme immediately, and get retrospective state aid approval."