China on Tuesday refused to comment directly on reports it was building a major underground nuclear submarine base, but defended its right to protect its maritime and territorial interests.
"We have a vast territorial sea, and it is the sacred duty of the Chinese army to safeguard our security on the sea, the sovereignty of our territorial waters, and maritime rights and interests," foreign ministry spokesman Qin Gang told reporters on Tuesday.
He was responding to questions about a report by Jane's Intelligence Review, a respected defence periodical, on Friday that said China was building the base near the holiday resort of Sanya on southern China's Hainan island.
Jane's reported it had confirmed the existence of the base through satellite images.
It said China's plans raised regional and global security concerns, partly because the vessels would be stationed so close to Southeast Asia's sea lanes.
Qin would not confirm nor deny the existence of the base, but insisted that China's military posed no threat to the world.
"There is no need for the Western countries to be worried, or concerned, or make any irresponsible accusations," Qin said.
"China's national defence and military building will not pose a threat to any countries."
Jane's said the base could mean China was preparing to house a large proportion of its nuclear forces, and even operate them from there, which could cause concern to regional powers and others further afield.
The positioning of China's most advanced underwater combatants at Sanya could have implications for China's control of the South China Sea and the strategically vital straits in the area, said Jane's.
"For both regional and extra-regional powers, it will be difficult to ignore that China is now building a major naval base at Sanya and may be preparing to house and protect a large proportion of its nuclear forces here and even operate them from this base," the group said.
"This development so close to the Southeast Asian sea lanes so vital to the economies of Asia can only cause concern far beyond these straits."
Britain's Daily Telegraph also reported on the base and called it a "vast, James Bond-style edifice capable of concealing up to 20 nuclear-powered submarines, which will enable China to project its power across the region."
