BEIJING -- The Chinese Ministry of Commerce said Friday it will extend anti-dumping investigations to high-performance stainless steel seamless tubes from the European Union and Japan for another six months.

In a statement on its website, the ministry said the extension was made due to the "specialty and complexity" of the case, adding that the probe will last until March 8 next year.

The ongoing investigations were announced by the ministry on September 8 last year.

Earlier in May, the ministry said in a preliminary ruling that the EU and Japan have been dumping high-performance stainless steel seamless tubes into the Chinese market and have "substantially harmed" Chinese producers.

Anti-dumping deposits paid to Chinese customs by the importers of those products are charged in accordance with dumping margins for different producers, with rates ranging from 9.7 percent to 39.2 percent of the customs value of the imported goods.