By Natalia Drozdiak and Laurence Norman 

BRUSSELS--A top European Union court on Tuesday rejected an appeal by Chinese solar panel companies to scrap anti-dumping and antisubsidy measures imposed by European Union member states in 2013 on imports of solar panels and essential components.

"The court rejects all the applications and confirms all the definitive duties set by the Council," the Luxembourg-based General Court of the EU said in a statement.

Separately on Tuesday, the commission also decided to impose definitive anti-dumping duties on imports of heavy steel plates from China, the latest action against the Asian country's exports.

The Council of European Union member states in December 2013 imposed definitive duties of an average of around 50% on imports of solar panels from China for a duration of two years, in one of the biggest-ever disputes over unfair trade under the decades-old regime of international trade rules.

The decision by the member states followed in-depth investigations by the European Commission, the bloc's executive, which found that Chinese companies were selling solar panels in Europe below their market price and were receiving illegal subsidies, to the detriment of EU solar panel manufacturers.

Twenty six companies affected by the anti-dumping duties, including subsidiaries of JA Solar Holdings Co, Ltd., brought legal action in 2014 against the EU Council's decision. They argued the court should annul the regulation on the basis of procedural inaccuracies in the anti-dumping investigations and other grounds.

The companies can still appeal the decision to the bloc's highest court, the Court of Justice.

The commission also said Tuesday that it was locking in place the temporary duties it imposed in October, taxing Chinese heavy steel plate imports with duties ranging from 65% to 73%.

"The commission has responded forcefully and quickly to unfair competition, while at the same time ensuring that the rights of all interested parties have been protected," it said in its press release.

Overcapacity in the steel sector has led to thousands of job losses in the European sector in the past year and has caused steel producers around the world to seek government protection from falling prices.

The EU now has 41 anti-dumping and antisubsidy measures targeting unfair imports of steel products. Eighteen of these target Chinese imports.

Write to Natalia Drozdiak at natalia.drozdiak@wsj.com and Laurence Norman at laurence.norman@wsj.com

(END) Dow Jones Newswires

February 28, 2017 07:17 ET (12:17 GMT)