BRUSSELS- The European Union is concerned that time is running out for the United States to remove tariffs imposed by former President Donald Trump on steel and aluminium, a senior EU trade official said on Thursday.

Citing U.S. national security grounds the Trump administration in 2018 imposed tariffs of 25% on EU steel and 10% on aluminium - measures that steelmakers such as Thyssenkrupp and Voestalpine have said they were affected by.

The EU denied its exports pose any security threat and responded by placing its own tariffs on 2.8 billion euros ($3.4 billion) of U.S. products, including motorbikes, whisky and orange juice.

"I'm very worried that we are running out of time," said Sabine Weyand, director-general of the trade section of the European Commission. "We had suggested and are suggesting still that we would also suspend tariffs for a period of six months to give us time to sort out the issues."

The Commission, which oversees EU trade policy, has said the U.S. tariffs affect 6.4 billion euros of EU metal exports. It said in 2018 it would "rebalance" the remaining 3.6 billion euros after three years, or after a finding in its favour by the World Trade Organization.

Those three years expire in June and its challenge at the WTO is ongoing.

"What I'm worried about is that we are on an automatic track to have the second tranche of our rebalancing measures come into force on June 1," Weyand told an online conference organised by the European Policy Centre

She said a solution needed to be found before then, which had to put the two sides on a path to addressing the root cause of the problems, which is Chinese overcapacity.

The United States and the EU suspended tariffs for four months from March in another trade dispute, over subsidies provided to planemakers Boeing and Airbus. 

($1 = 0.8358 euros)

(Reporting by Philip Blenkinsop Editing by David Holmes) ((philip.blenkinsop@thomsonreuters.com; +32 2 585 2869; Reuters Messaging: @reutersPhilB))