China reiterates islands claim after Philippine UN move
China has reiterated its claim to a group of islands in the South China Sea, saying it has "indisputable sovereignty" over the area.
The move comes after the Philippines said it had exhausted diplomatic avenues and was seeking UN arbitration over the competing territorial claims.
Beijing accused the Philippines of illegally occupying the area.
Tensions between the two have been high since a stand-off at the Scarborough Shoal - which both claim - last year.
China claims a U-shaped swathe of the South China Sea; its claims overlap those of several South East Asian nations.
On Tuesday, the Philippines Foreign Secretary Albert del Rosario said Manila would take Beijing to an arbitration tribunal under the United Nations Convention on the Law of the Sea (UNCLOS), which both had signed.
In a statement, he said China had "interfered with the lawful exercise by the Philippines of its rights within its legitimate maritime zones" and that the Philippines wants the tribunal to declare China's so-called "nine-dash line" invalid.
On Wednesday, Chinese foreign ministry spokesman Hong Lei told journalists that China has "indisputable sovereignty over the South China Sea islands and adjacent waters, which has abundant historical and legal grounds".
"The key and root of the dispute over the South China Sea between China and the Philippines is territorial disputes caused by the Philippines' illegal occupation of some of the Chinese islets and atolls of the Spratly Islands," he said.
He said China had been "consistently working towards resolving the disputes through dialogue and negotiations to defend Sino-Philippine relations and regional peace and stability".
The row between Manila and Beijing has been rumbling since April 2012, when government vessels from both nations faced off for several weeks at the Scarborough Shoal.
Since then both the Philippines and Vietnam - which is in dispute with China over the Paracel islands - have sought to raise the issue through the Asean regional bloc, but claim Chinese pressure has forced the topic off the agenda.
China has in the past preferred to handle disputes on a bilateral level, rather than through regional groupings or international organisations.
In recent months Beijing has taken a more assertive posture on the issue, leaving ties with both the Philippines and Vietnam severely strained.
China's claim includes almost the entire South China Sea, well into what UNCLOS recognises as the 200-mile-from-shore Exclusive Economic Zones of other claimants.
As well as the Philippines and Vietnam, Brunei, Malaysia and Taiwan have overlapping claims.