The European Union has unveiled plans to raise tariffs on imported steel, sparking alarm in the United Kingdom's beleaguered steel industry.

The EU's executive arm, the European Commission, has outlined proposals to halve the volume of steel that can be imported into the bloc, above which a new 50 percent tariff would apply.

As the UK's most important steel export market, the EU accounts for 78 percent of British steel sold overseas, worth nearly 3 billion pounds ($4 billion).

The EU proposes cutting duty-free import quotas to 18.3 million metric tons a year, which would be a 47 percent decline from 2024 levels.

Because of rising imports and United States tariffs, EU steel producers are operating at only 67 percent of capacity and the new measures are designed to push that up toward 80 percent.

The European Commission said on Tuesday that the measures respond to calls from workers, industry and several member states "to offer strong and permanent protection to the EU steel industry, with a view to safeguarding EU jobs, and supporting the sector in its decarbonization efforts".

The measures are slated to take effect early next year, pending approval by a majority of EU member states and the European Parliament. The proposals would supersede the current steel safeguard, which is set to expire in June, CNBC reported.

Another setback

The move would be another setback for the UK steel sector after a deal to eliminate US tariffs was indefinitely paused last month, and after the government earlier this year took over plants in the English towns of Scunthorpe, Rotherham and Stocksbridge that were in financial distress.

In response to the EU's announcement, Gareth Stace, director general of industry body UK Steel, said, "This is perhaps the biggest crisis the UK steel industry has ever faced."

The government "must go all out to leverage our trading relationship with the European Union to secure UK country quotas or potentially face disaster", Stace added.

He warned that the EU's plans risk "redirecting millions of tons of steel toward the UK", which could be "terminal for many of our remaining steel companies".

Speaking en route to India on Tuesday, UK Prime Minister Keir Starmer said the government was in discussions about the implications of the proposed tariffs and potential mitigation, and pledged "strong support" for the industry.

In a statement, the UK's Department for Business and Trade said it was "pressing the European Commission for urgent clarity on the impact of this move on the UK".

Maros Sefcovic, European commissioner for trade and economic security, said he would "fully engage" with the UK and floated the possibility of a future UK-specific quota.

Meanwhile, South Korea's industry ministry said in a statement on Wednesday that the European Commission's proposal would negatively affect the country's steel exports if implemented as planned.

The proposal is expected to have "significant impact" on steel exports to the EU, which is South Korean steelmakers' second-largest export market, the ministry said.

"However, since the EU has explicitly stated that it will consider FTA (free trade agreement) signatory countries when allotting supplies by country, South Korea plans to secure our interests as much as possible through bilateral consultations," the ministry said.

South Korea's top trade envoy Yeo Han-koo plans to meet Sefcovic in the coming days to express the country's position, the ministry added.

Reuters contributed to this story.