Tensions over disputed archipelago continue. The deputy chairman of China's Central Military Commission tells soldiers to be "prepared". Celebrations marking 40th anniversary of the normalisation of relations between the two countries could be cancelled.

Beijing (AsiaNews/Agencies) - Six Chinese surveillance ships have entered waters near the Diaoyu/Senkaku Islands, escalating the diplomatic row between both China and Japan. At least two of the vessels turned back after the Japanese coast guard issued a warning. No force was used, a Japanese coast guard official said; however, China's action proves contentious.

Japanese Prime Minister Yoshihiko Noda said his government was taking "all possible measures" to ensure security around the islands, quickly mobilising a task force at the crisis management centre in Prime Minister's Office.

Japan's Deputy Foreign Minister Chikao Kawai summoned Chinese Ambassador to Japan Ting Yonghua to the ministry to lodge a protest.

For Beijing, the ships' presence is a legitimate response to the Japanese government's decision to purchase the islands from their private owners.

Xinhua quoted Xu Caihou, deputy chairman of China's powerful Central Military Commission, telling soldiers to be "prepared for any possible military combat".

Although Xu made no mention of the territorial dispute with Japan, he did say that "Efforts should be made to ensure that the military is capable of resolutely performing its duty to safeguard the country's national sovereignty, security and territorial integrity whenever it is needed by the Party and the people".

The rising tensions over the disputed islands are threatening celebrations to mark the 40th anniversary of the normalisation of relations between Beijing and Tokyo. Until 1972, the two countries had not had diplomatic ties.

Various events are scheduled for 27 September, the day when the countries established relations. However, a number of high profile Japanese political leaders announced they would not attend.

The value of the disputed islands is unclear. They are strategically important as a crossroad to several maritime routes and some experts believe they have rich fishing grounds and that the seabed around them holds vast gas reserves.

In 2008, as an act of détente, the two governments signed an agreement to develop the area jointly, but it came to naught.

• china
• japan
• disputed
• islands
• diaoyu
• senkaku