The European Commission (EC) is to impose anti-dumping duties on imports of two steel products from China.
The commission said the move was a "swift reaction" to unfair competition, an issue which has badly hit the UK steel industry, threatening job losses.
The measures affect hot-rolled flat steel and heavy plates of steel, and follow an investigation by the EC.
A statement said: "The Commission's investigations confirmed that the Chinese products had been sold in Europe at heavily dumped prices.
"To provide EU companies with necessary breathing space, the Commission imposed duties ranging between 65.1% and 73.7% for heavy plates and 13.2% and 22.6% for hot-rolled steel.
"This should restore the profitability of the European heavy plates' producers and prevent damage to the companies involved in the production of hot-rolled steel products."
The announcement came as steelworkers' union Community spoke out against "further delays and uncertainty" over the sale of Tata's Speciality Steels business in South Yorkshire.
The company has announced that the division, which employs more than 2,000 workers in Rotherham and Stocksbridge, will be sold separately from its other business.
Community said workers did not know if their jobs were safe after months of rumours.
General secretary Roy Rickhuss said: "While so much focus is on the sale of Tata's strip business and the uncertainty surrounding the pension scheme, Community will not allow Speciality Steels to become the forgotten part of the steel crisis.
"With over 2,000 direct employees and many thousands more in the local supply chain, this business is of huge importance to the South Yorkshire region.
"When Tata announced that they wanted to sell the business, we called on them to act as a responsible seller. The continued lack of information about that process and the worry this has caused amongst their loyal workforce is highly irresponsible."
A Tata Steel spokesman said: "Whenever we have significant news we always seek to tell our employees first. We also communicate regularly with our employees about issues which could affect them, including through briefings and newsletters.
"We strive to maintain strong relationships with all our key stakeholders, including trade unions and local MPs around our UK sites.
"Discussions have been ongoing with a number of interested parties regarding the sales process of our Speciality Steels business since our announcement in July. Bidders have been given the opportunity to meet with management and conduct site visits, as well as having access to information to assist in performing due diligence.
"The process is ongoing and we will provide a further update at the appropriate point."
Dominic King, head of policy at trade group UK Steel, said: "The speed at which tariffs have been imposed on dumped steel from China by the EU today is welcomed; however, the duty levels are still inadequate, especially when compared with the firm action taken by the US.
"Steel producers in the UK have experienced first-hand what happens when trade is not free and fair and the UK Government will soon have the ability to match words with actions to ensure dumping of steel doesn't take place on our shores."
Newly appointed shadow business secretary Clive Lewis said: " This is a small step in the right direction but it's no thanks to Tory ministers, who have consistently failed to take action to defend our steel industry, whether in Europe or in Britain.
"Months after Labour proposed a four-point plan for steel, workers are still waiting for answers on the future of their jobs, communities and industry, and we have already lost thousands of jobs. Instead of leaving it to others, the Government needs to step in and take action to secure the future of a critical sector for our economy."
Unite national officer Harish Patel said: "It has taken time coming, but this move by Europe against the dumping of cheap Chinese steel will be a welcome relief for UK steelworkers battling to keep the industry afloat.
"It will only be temporary relief though, unless the Government commits to similar anti-dumping measures post-Brexit as part of an active industrial strategy which protects and promotes UK steel and British manufacturing."
Mr Rickhuss, of the Community union, said of the EC announcement: "We welcome this move but this sort of action must be taken quicker against unfairly traded steel from China or anywhere else.
"In the aftermath of the Brexit vote, the UK Government must commit to ensuring Britain has robust trade defences against Chinese dumping after we leave the EU."
A Government spokesman said: "We have been pressing for greater urgency from the Commission, so it's encouraging to see these tariffs being imposed more rapidly.
"As well as supporting our steel industry by tackling unfair steel dumping, we have also been encouraging greater use of British steel in public infrastructure projects, and we have taken action on energy costs.
"We are focused on working with the industry and partners on safeguarding the long-term sustainable future of the steel industry in the UK."