China's state news agency says Japan has released a Chinese fishing crew detained on Saturday for poaching in Japanese waters.

Xinhua said Japanese authorities released the captain and his crew on Monday, after detaining them in waters off the southern city of Kagoshima.

A Chinese foreign ministry official said Beijing sent a diplomat to a Japanese detention facility in Kagoshima to ensure the fishing crew's rights were protected.

Xinhua said the Chinese fishermen promised to pay a $50,000 fine for illegal coral fishing before being allowed to depart for China.

Chinese fishing boats often venture into waters far east of mainland China due to depleted fishing stocks closer to the coast.

Japan-China tensions escalated this year as the two major trade partners asserted their rival claims to sovereignty over a resource-rich archipelago in the East China Sea.

Japan's coast guard said it spotted three Chinese government ships in waters near the disputed Japanese-controlled islands on Monday. Chinese vessels repeatedly have sailed near the islands in recent months, ignoring Japanese coast guard warnings to stay out. The islands are known as Senkaku in Japan and Diaoyu in China.