China is "gravely concerned" about the statement issued after the ASEAN Summit on the South China Sea issue, Chinese foreign ministry spokesperson Hong Lei told a news conference on Tuesday.

The chairman's Statement of the 26th ASEAN Summit released Tuesday expressed serious concerns about China's island-building activities in the South China Sea and re-affirmed the importance of maintaining peace and the right of navigation.

"China firmly upholds territorial sovereignty and maritime rights and interests," Hong said. The construction work on the Nansha islands is lawful, justified and beyond reproach, according to Hong.

"China's construction on the islands and reefs of Nansha is completely within China's sovereignty, and does not target or affect anyone," he noted.

"There has never been any problem concerning the freedom of navigation and over-flight in the South China Sea that all countries are entitled to under international law. Nor will there be any in the future," Hong stressed.

Hong urged all the countries concerned to meet China halfway, to safeguard the peace and stability of the South China Sea region and the general interests of the China-ASEAN relationship.

"The Chinese side opposes a few countries' taking hostage the entire ASEAN and China-ASEAN relations for their own selfish gains," he said.