China claims almost the entire South China Sea, rejecting rival claims to parts of it from Vietnam, the Philippines, Taiwan, Malaysia and Brunei in one of Asia's most intractable disputes and a possible flashpoint. It also has a separate maritime dispute with Japan over islands in the East Sea.
Japanese Prime Minister Shinzo Abe on Thursday expressed concern about regional tensions that he said were stoked by China's "unilateral drilling" after China moved a giant oil rig into disputed waters, a moved denounced by the Philippines, Vietnam and the United States.
"The relevant Japanese statement neglects reality and confuses the facts, and takes a political motive to interfere with the situation in the South China Sea for a secret purpose," Chinese Foreign Ministry spokesman Hong Lei told a daily briefing.
"We require the Japanese side to consistently take realistic actions to protect the region's peace and stability."
The Philippines blamed a slowdown in talks on ending the disputes on "construction" changing the ground rules, an apparent reference to China.
The Philippines is pushing for a "code of conduct".
"The code of conduct has been long in coming, we have been discussing this for the past seven or eight years, and we're also wondering why there is a delay," Philippine Foreign Ministry Undersecretary Laura del Rosario said.
"Are we changing the environment so that when we are ready to discuss the code of conduct, the environment has changed?"
Del Rosario, speaking at a security outlook session of the World Economic Forum, said there had been "changes" on the ground since talks began, without specifically mentioning China.
"There are a lot of build-ups, a lot of construction going on, until we realise people are already doing some kind of a fencing."
Last week, the Philippine foreign ministry released aerial surveillance pictures of a reef showing what it said was Chinese reclamation and the building of what appeared to be an airstrip.
SLOWING THE TALKS
A Malaysian diplomatic source said China was deliberately slowing down the talks.
"China has been reluctant to even talk about the code of conduct," the diplomatic source said. "It's a carrot to dangle in the distance. We are dealing with a superpower."
Vietnamese Prime Minister Nguyen Tan Dung said his government was considering various "defence options" against China, including legal action, following the deployment of a the oil rig.
Dung's comments, given in a written response to questions from Reuters, were the first time he has suggested Vietnam would take legal measures, and drew an angry response from China.
Anti-Chinese violence flared in Vietnam last week after the $1 billion deepwater rig owned by China's state-run CNOOC oil company was parked 240 km (150 miles) off the coast of Vietnam.
Hanoi says the rig is in its 200-nautical mile exclusive economic zone and on its continental shelf. China has said the rig was operating completely within its waters.
"We prepared all possible measures, including legal measures," Nguyen Thi Thanh Ha, head of Vietnam's Foreign Ministry legal department, said on Friday.
"Using legal measures is better than armed conflict."