THE US sees China's introduction of an oil rig and several vessels in waters disputed with Vietnam as "provocative", US Secretary of State John Kerry has told China's foreign minister in a telephone call.

China claims almost the entire South China Sea, rejecting rival claims to parts of it from Vietnam, the Philippines, Taiwan, Malaysia and Brunei.

US State Department spokeswoman Jen Psaki said: "He (Kerry) said China's introduction of an oil rig and numerous government vessels in waters disputed with Vietnam was provocative.

"He urged both sides to de-escalate tensions, ensure safe conduct by their vessels at sea, and resolve the dispute through peaceful means in accordance with international law."

China's foreign ministry said there had been provocative moves in the South China Sea but China was not the guilty party.