(CNN) -- China warned Sunday that it would take "strong counter measures" against Japan if a Chinese fishing captain held since last week is not released.
The captain was arrested earlier this month off the disputed Diaoyu Islands, in the East China Sea, after his vessel crashed into two Japanese patrol boats. He remains in custody, accused of obstructing Japanese public officers while they performed duties.
"We demand the Japanese side immediately release the Chinese captain unconditionally," said Foreign Ministry spokesman Ma Zhaoxu, the state-run Xinhua news agency reported.
China has already suspended bilateral exchanges at and above the provincial or ministerial levels, Xinhua reported.
The country has also stopped talks with Japan about increasing civil flights and expanding aviation rights between the two countries, the news agency said.
A bilateral meeting on coal was also postponed, Xinhua reported.
"China will take strong counter measures if the Japanese side clings obstinately to its own course and double its mistakes, and Japan shall bear all the consequences," Ma said in a press statement.
Japan has already freed the captain's 14 crew members, who have flown back to China, and returned the fishing boat as well.
The incident has raised tensions between the two countries and their citizens.
In Beijing, Shanghai and Shenyang on Saturday, anti-Japanese protests were held. The Japanese Embassy in China has warned Japanese citizens in China to be on guard.
"China has reiterated time and again that Japan's so-called legal procedures against the captain were illegal and invalid," Ma said. "We demand the Japanese side immediately and unconditionally release the captain. Or the Japanese side must shoulder all consequences that arise."