China has sent two patrol ships to a group of islands at the centre of a territorial row with Japan

China has sent two patrol ships to a group of islands at the centre of a territorial row with Japan, state news agency Xinhua reported Tuesday, after Tokyo said it would nationalize them.
  
Xinhua said the two marine surveillance ships had reached the waters around the Diaoyu islands -- known in Japan as the Senkaku islands -- to "assert the country's sovereignty".
  
The latest move came hours after Beijing said late Monday it had summoned the Japanese ambassador to protest Tokyo's announcement that it will buy three of the islands, which will be formally owned by Japan's Coast Guard.
  
Chinese Premier Wen Jiabao said the islands were "an inherent part of China's territory" and vowed his country would "never ever yield an inch" on its sovereignty.
  
The islands lie around 200 kilometers (125 miles) from Taiwan, and 2,000 kilometers from Tokyo, in a strategically important shipping area. Valuable mineral resources are thought to be nearby.