China on Friday said it opposed the Philippines' plan to offer oil exploration contracts in the South China Sea, urging the country not to escalate tensions in the area.

"China has repeatedly lodged representations with the Philippines for their bidding out oil exploration contracts in some of the blocs which has violated China's interests," said Chinese Foreign Ministry spokesman Liu Weimin at a regular press briefing.

"Without permission from the Chinese government, oil exploration activity by any country or any company in waters under China's jurisdiction are illegal," said the spokesman.

Liu's comments came in response to a question regarding remarks of the Philippine Energy Undersecretary James Layug at the sidelines of an energy forum in Manila on Wednesday.

Layug was quoted by media as saying the Philippines will offer oil exploration contracts for the three blocs in the South China Sea on July 31, which are off the coast of the western Philippine island of Palawan.

According to James Layug, all reserves in that area belong to the Philippines and China had not objected to the plans to bid out the contracts for the three blocs.

"China urges the Philippines to adhere to the principal of the Declaration on the Conduct of Parties in the South China Sea, and not to take action that may lead to complication and escalation of tensions," Liu said.

The spokesman called on the Philippine side to make its due contribution to maintaining peace and stability of the South China Sea.

During the China-ASEAN Foreign Ministers' Meeting held in Phnom Penh of Cambodia on Wednesday, China and ASEAN countries had discussions and reached consensus on the South China Sea issue.

Chinese Foreign Minister Yang Jiechi said China calls for shelving disputes and seeking joint development on the South China Sea issue, and hopes all parties will do more to enhance mutual trust and promote cooperation for the formulation of a code of conduct in the South China Sea.