ALJAZEERA, 14 Sep 2012 09:20

Six Chinese ships have sailed into waters around a disputed archipelago, with Beijing saying they were there for "law enforcement" around islands Japan nationalised earlier this week.

The move, dubbed "unprecedented" by Tokyo, came on Friday as it was reported Japanese nationals had been physically attacked in China, marking the latest stage in a deteriorating row between Asia's two biggest economies.

Japanese living or visiting China were warned to take extra precautions after assaults and harassment were reported to the consulate in Shanghai, a base for Japanese businesses and a popular tourist destination.

Tokyo summoned the Chinese ambassador to protest what it insists is an incursion into territorial waters around islands it controls, called Senkaku, but claimed by Beijing as Diaoyu.