BRUSSELS, June 22 (Reuters) - The European Union is set to continue a system of quotas and tariffs that have been in place since 2018 for a further three years to protect EU steelmakers from a potential surge of imports.

Washington's retention of 25% steel tariffs has closed the U.S. market to many exporters, prompting the European Union to put in place safeguard measures for 26 grades of steel, including stainless, with imports over the quota thresholds subject to tariffs. The quotas have increased each year.

Twelve EU countries, including France, Germany and Italy, urged the European Commission in January to extend the safeguard measures beyond their June 30 expiration date.

The Commission, which oversees EU trade policy, has reviewed the measures and proposed a three-year extension, with the quotas rising by 3% at the start, as well as in 2022 and 2023. EU members have since approved it, EU diplomats said.

Since the safeguards will have lasted beyond three years, those subject to the quotas can, under World Trade Organization rules, bring counter-measures such as tariffs on EU goods.

The main exporters of steel to the EU are China, India, Russia, South Korea, Turkey and Ukraine. (Reporting by Philip Blenkinsop, editing by Louise Heavens)