Washington and Tokyo are in the final stage of talks to exempt a portion of U.S. imports of steel from Japan from extra tariffs imposed in 2018 by U.S. President Donald Trump, sources close to the matter said Saturday.

The two countries are discussing establishing a tariff-free import quota but its size and some other details have yet to be finalized, the sources said.

The United States has levied additional duties of 25% on steel and 10% on aluminum imports since 2018, when the Trump administration cited potential national security risks under its "America First" foreign and trade policy.

The two countries will continue discussions on the levies on aluminum imports, according to the sources.

The Trump administration also imposed additional tariffs on steel and aluminum from the European Union, but the EU took retaliatory measures against U.S. imports.

The two sides agreed last October to introduce a tariff-free import quota for a certain amount per year. U.S. tariffs would apply to annual volumes above 3.3 million tons of steel from the EU, Reuters reported citing sources familiar with the deal.

Japan has been asking for exemptions from the Trump-era tariffs. Last November, trade minister Koichi Hagiuda and U.S. Commerce Secretary Gina Raimondo agreed to launch negotiations.

The United States is particularly concerned about the impact on its economy of what it says is excessive steel production by China.