Japan’s coast guard has fired water cannons at a Taiwanese boat transporting a group of activists to the disputed islands in the East China Sea.

“After entering our country’s contiguous zone, the vessel with foreign activists on board continued sailing east. So our patrol boat carried out restrictions on the vessel such as blocking its path and discharging water,” the coast guard said in a statement on Thursday.

The firing took place when the Taiwanese boat was around 32 kilometers (20 miles) west-southwest of the Senkaku Islands, known in Japan, or Diaoyu Islands, known in China.

“The vessel left our country’s contiguous zone at around 1:30 p.m. (0430 GMT) and continued sailing west-southwest away from the Senkakus,” the coast guard said.

The seven activists set sail for the isles during the early hours of Thursday.

Japan and China have long been in a dispute over the sovereignty of the islands, which would give the owner exclusive oil, mineral and fishing rights in the surrounding waters.

Hsieh Mang-lin, the Taiwanese chairman of the Chinese Association for Protecting the Diaoyutais (Diaoyu Islands), said in a statement that the group intended to “maintain sovereignty” against Japan’s control.

In September 2012, Japanese and Taiwanese coastguard vessels dueled with water cannon after dozens of Taiwanese boats were escorted by patrol ships into the waters around the archipelago.

China’s National Administration of Surveying, Mapping and Geoinformation said a few days ago that Beijing was set to carry out a detailed survey of the disputed isles.

The administration said the geographical survey was part of a comprehensive program to map the country’s “territorial islands and reefs.”

The announcement came a day after Japanese media said Tokyo would deploy two more patrol ships near the disputed islands for defensive purposes.

The islands are controlled by Japan and form part of Okinawa prefecture.

Tensions heightened between the two countries after Japan signed a deal on September 11, 2012 to buy three of the islands from their private Japanese owner in line with plans to nationalize the archipelago.

MSH/HSN