Calling the patrol of Chinese ships near Diaoyu Islands - its own territorial seas - irreproachable, the government yesterday said the recent dispute would not cast a shadow on the forthcoming trilateral summit between Beijing, Tokyo and Seoul.

Japan on Monday lodged a protest with Beijing after two Chinese survey ships reportedly spent nine hours in East China Sea waters near the Diaoyu Islands.

"I cannot accept China has done anything provocative by patrolling in its own territorial sea. The Diaoyu Islands and adjacent islets are Chinese territory," Liu Jianchao, the Foreign Ministry spokesman, said yesterday.