A Japanese court on Thursday dismissed charges against a Chinese trawler captain over the 2010 ramming of two coastguard vessels off disputed islands that triggered a diplomatic crisis, reports said.

Japanese authorities arrested Zhan Qixiong, 42, after the incident near the islands, known as Senkaku in Japan and Diaoyu in China, but the move infuriated Beijing and he was released a few weeks later to return home.

Prosecutors later dropped the case against Zhan, only for an independent panel to decide he should be charged, and he was indicted this March.

But the Naha district court formally dismissed the indictment as it was not served on the skipper within the two-month limit, Kyodo News reported.

The agency cited the court as saying Beijing refused to deliver the charge sheet to the defendant on the grounds the islands are Chinese territory.

Beijing has become increasingly emphatic in asserting its territorial claims in the East and South China Seas in recent years, causing growing alarm in the region and further afield.