Japan is considering using spy drones to boost surveillance near islands in the East China Sea at the centre of a territorial dispute with Beijing.
Kyodo News reported the defence ministry hopes to introduce unmanned Global Hawk aircraft by 2015 "to counter China's growing assertiveness at sea, especially when it comes to the Senkaku Islands".
Beijing has been sending maritime patrol vessels into waters around the islands, which China claims as Diaoyu, since Tokyo nationalised them in September.
AAP says China is apparently seeking to prove that it can come and go in the area at will.
On Monday three Chinese ships were spotted in the waters around the islands, according to the Japanese coastguard.
An earlier report on Monday said China has transferred two destroyers and nine other former navy vessels to its maritime surveillance fleet.
Fishing boat detained
The BBC reports a Chinese fishing boat was detained by Japanese coastguard for fishing inside Japanese waters on Saturday.
Xinhua news agency said the boat was seized near the Kagoshima Prefecture. Xinhua said the captain had admitted entering Japanese waters.
The captain and two crew members have been taken to Kagoshima for questioning. Six other sailors remained on board the boat, which comes from Fujian province in south-east China.
A Chinese consulate official has been sent to Kagoshima to visit them.