The Japanese coastguard said the Chinese vessels entered the 12-nautical-mile band of territorial waters around one of the Senkaku islands, which China also claims and calls the Diaoyus, shortly before noon (0300 GMT).
It was the third such incursion since US President Barack Obama vigorously reasserted on April 24 that Washington would defend Japan under a bilateral military treaty if China initiated an attack in the tense dispute.
China has already dismissed Obama's position, saying that the islands are "China's inherent territory".
Chinese vessels and aircraft regularly approach the East China Sea archipelago - thought to harbour natural resources - after Japan nationalised some of the islands in September 2012, setting off the latest spate of incidents in a long-running territorial dispute.
Relations between Tokyo and Beijing have fallen to their lowest point for years.
RESULT
TOKYO: Three Chinese coastguard ships sailed into disputed waters in the East China Sea on Friday as Beijing maintained its defiant stance after US
China ships enter waters off disputed islands: Japan ...
China ships enter waters off disputed The Chinese coastguard ships entered the waters off one of China ships in disputed waters: Japan coastguard;
Chinese ships enter disputed waters: Japan coastguard
Three Chinese coastguard ships sailed through disputed waters in the East China Sea Friday as Beijing maintained its defiant stance after US President Barack Obama
Chinese ships enter disputed waters: Japan coastguard ...
Chinese ships enter disputed waters: Japan coastguard The writer has posted comments on this article AFP | May 2, 2014, 11.30 AM IST
China ships enter disputed waters: Japan coastguard | Fox News
Chinese coastguard ships on Friday sailed into disputed waters at the centre of a bitter row with Tokyo, officials said, a day after China blasted Japanese
Chinese ships enter disputed waters: Japan coastguard ...
Taiwan reiterates its sovereignty over islands after US statement favours Japan; Chinese ships return to disputed waters after Obama's Tokyo visit
Chinese ships enter disputed waters: Japan coastguard
Chinese ships enter disputed waters: Japan coastguard. This is the third such incursion since US President Barack Obama reasserted that Washington would defend Japan
China ships enter waters off disputed islands: Japan ...
Three Chinese coastguard ships have sailed through disputed waters off Tokyo-controlled islands in the East China Sea on Saturday, the Japanese coastguard
Chinese coast guard ships enter disputed waters Japan ...
TOKYO Chinese ships sailed through disputed waters off Tokyo-controlled islands on Monday, days after Japans Prime Minister Shinzo Abe caused an international
Chinese ships enter disputed waters: Japanese coastguard ...
Three Chinese coastguard ships sailed into disputed waters in East China Sea Friday as Beijing maintained its defiant stance.
