China said Thursday it was imposing duties on steel tube imports from the European Union and Japan as it concluded an investigation into products it says were sold at prices below market levels.

The move is the latest volley in a slew of trade rows between China and its key trade partners that have seen tit-for-tat duties put on a range of goods.

The duties -- ranging from 9.2 to 14.4 percent -- on specialised stainless steel tubes sold by European and Japanese companies for five years will kick in on Friday, the Ministry of Commerce said in a statement.

The final ruling on the case cut the rate of the anti-dumping taxes sharply from the 9.7-39.2 percent set in the ministry's preliminary decision announced in May. The tubes are mainly used in industrial boilers.

The probe, started in September last year, found imports of the products caused "substantive harm" to Chinese industry, the ministry said, keeping unchanged an opinion stated in the May ruling.

European and Japanese firms affected by the case in May were required to pay a deposit based on the preliminary ruling. They may get a refund after the final decision's cut in the rates, according to Chinese anti-dumping laws.

China, the world's top exporter, is at loggerheads with its main trade partners over a number of disputes with its sales of automobiles, rare earth minerals and solar cells.

The European Commission announced Thursday it had opened a probe into subsidies given to Chinese solar panel makers, following a September decision to investigate the firms' alleged selling of the cells below actual cost.

The United States has also announced hefty anti-dumping and anti-subsidy duties on the products.

The World Trade Organization last month established a panel of experts to investigate a complaint by the United States over Chinese duties on auto imports. China announced last December it would impose anti-dumping duties on US-imported vehicles with engines of 2.5 litres or larger.

The EU, the US and Japan, meanwhile, asked the WTO in June to help resolve a dispute over Beijing's export controls on rare earths, used in the making of high-tech products including smartphones.

China currently produces more than 90 percent of the world's supply of the minerals, but has restricted exports in a move Beijing says is to protect its environment and conserve supplies.

But Japan, the European Union and the United States claim China is unfairly benefiting its own industries by clamping down on exports.