BEIJING China called off planned talks with Japan over an undersea gas bed dispute and warned of worse repercussions while Japan lodged a protest on Saturday over another maritime spat between the two big neighbors.
The Chinese Foreign Ministry issued its vehement warning after a Japanese court on Friday authorized a 10-day extension in detaining a Chinese captain whose fishing boat collided with two Japanese coast guard ships in disputed seas this week.
The arrest of the captain and continued detention of 14 crew members has given an emotive focus for long-running territorial quarrels between Beijing and Tokyo over East China Sea islets, called Senkaku in Japan and Diaoyu in China.
Later on Saturday, Japan lodged a protest with China after a Chinese State Oceanic Administration ship attempted to stop a Japanese Coast Guard vessel from conducting an oceanic survey 280 km northwest of Japan's southern Okinawa island.
The spokesman said the Japanese vessel was operating in Japan's exclusive economic zone and remained in the area after finishing the survey.
Asia's two biggest economies are also at loggerheads over gas beds under another part of the sea.
Chinese Foreign Ministry spokeswoman Jiang Yu responded angrily to the Japanese court's decision.
Beijing postponed a round of talks with Tokyo intended to eventually settle their dispute over East China Sea gas fields, she said in a statement on the Chinese Foreign Ministry web site (www.mfa.gov.cn) late on Friday.
The talks had been set for mid-September.
Jiang warned that worse may follow but gave no details.
"Japan has ignored China's many solemn representations and staunch opposition, and obstinately decided to impose so-called judicial procedures on the Chinese captain. China expresses its strong dissatisfaction and solemn protest," Jiang said.
"Japan's actions have violated international law and rudimentary common sense in international matters. They are absurd, illegal and invalid.
"If Japan continues in this reckless fashion, it will taste its own bitter fruit," Jiang said.
A source in the Japanese prime minister's office said it was "regrettable that a postponement (of the talks) was announced unilaterally," the Kyodo news agency said.
Relations between Beijing and Tokyo have long been dogged by mutual distrust and Chinese bitterness over Japan's occupation of much of China before and during World War Two.
Chinese media have warned that public opinion could become riled by the arrest and Beijing's official stand appeared partly intended to ward off accusations of weakness from angry citizens.
On Saturday morning, more police officers than usual guarded the Japanese embassy in Beijing, but only a small group of about 10 people gathered briefly in the afternoon before dispersing.
China's ruling Communist Party is wary of any street protests and usually makes certain that any demonstrations aimed at Japan are small and tightly guarded.
Tokyo has also lodged protests with Beijing over the incident and Japan's government spokesman earlier urged calm. Japan has not said whether it plans to prosecute the captain or how long it intends to hold the crew members in detention.
Broader contention over the disputed seas could unsettle ties between Asia's two biggest economies. Since big public protests and bitter diplomatic exchanges sparked rows in 2005 and 2006, both sides have sought to improve ties.
Tokyo maintains that China's exploration for natural gas in the East China Sea threatens gas beds extending under what it deems Japan's maritime zone. China denies there is such a problem and disputes Japan's definition of the sea boundary.
In 2008, they agreed in principle to solve the dispute by jointly developing gas fields. Talks began in July on a treaty, but the postponement of the next round of talks will hold back prospects for progress in the dispute.
(Additional reporting by Masayuki Kitano in TOKYO; Editing by Ken Wills and Ron Popeski)