China on Sunday said it had suspended senior bilateral exchanges with Japan over an incident in disputed waters and warned relations with Tokyo had been "severely hurt".
The announcement comes after a Japanese court authorised prosecutors to extend by 10 days the detention of a Chinese captain accused of ramming his trawler against Japanese patrol boats in the East China Sea.
It also comes as Chinese Premier Wen Jiabao and his counterpart Naoto Kan prepare to fly to New York to attend a UN gathering where they will meet US President Barack Obama in separate talks.
"China has already suspended bilateral exchanges at and above the provincial or ministerial levels," the official Xinhua news agency quoted the foreign ministry as saying Sunday.
Ministry spokesman Ma Zhaoxu threatened Japan with "strong counter-measures" if the captain was not released.
According to Xinhua, China has also halted contact with Japan on increasing civil flights between the two countries, adding a meeting on coal has also been postponed.
Japanese authorities arrested Zhan Qixiong, the Chinese captain, on September 8, but they have since released his crew and boat.
Zhan's initial detention on suspicion of obstructing official duties had been set to end Sunday.
Xinhua also reported that Chinese Vice Foreign Minister Wang Guangya made "solemn representations" to Japanese ambassador to China Uichiro Niwa on Sunday evening over Zhan's extended detention.
"The incident created by the Japanese side has severely damaged China-Japan relations," Wang was quoted as saying.
"Japan shall bear all the consequences that arise," he added.
The incident took place near the disputed Diaoyu islands -- called Senkaku in Japan and also claimed by Taiwan -- which lie in an area with rich fishing grounds that is also believed to contain oil and gas deposits.
China has already summoned Japan's ambassador five times and scrapped scheduled talks over joint energy exploration in the East China Sea, in what has become the worst diplomatic row in years between Beijing and Tokyo.
Ma on Sunday reiterated Beijing's stance that the detention was "illegal and pointless." Xinhua quoted the foreign ministry as saying relations with Japan had been "severely hurt".
"We ask Japan to immediately and unconditionally release the Chinese captain," Ma said in a statement.
The incident has sparked resentment among the Chinese public, which still has strong feelings about atrocities committed by Japanese forces when they occupied swathes of northern China before and during World War II.
On Saturday, the anniversary of Japan's 1932 invasion of Manchuria, protesters rallied in Beijing, Shanghai and Hong Kong, although the demonstrations were relatively small, short and non-violent.
Security was still tight in the area around the Japanese embassy in Beijing, in possible anticipation of fresh protests.
Earlier Sunday, Japanese Foreign Minister Seiji Maehara tried to ease the impact of the incident, saying that China had helped restrain the demonstrations, which he called "sporadic protest activities".
"I think the Chinese government has made considerable efforts to restrain them," he said in a televised talk show. "In this sense, it is imperative for both sides to deal with the matter in a level-headed manner."
He also described the collision as "gu-hatsuteki" -- a Japanese word which could be translated as incidental or unforeseen.
The expression was apparently softer than Tokyo's earlier position that the captain intentionally rammed the Japanese vessels during a high-seas chase on September 7.
Tokyo has warned its citizens in China to remain vigilant to ensure their safety in the event of any backlash over the dispute.
AFP/ir/fa
