China on Friday frowned on reported plans by the Philippines to offer oil exploration contracts in the West Philippine Sea, even as it reminded Manila not to escalate tension in the area.

A report posted on the Chinese government's web portal early Saturday quoted Chinese Foreign Ministry spokesman Liu Weimin as saying any exploration without China's permission will be illegal.

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

He added China has repeatedly lodged representations with the Philippines for their bidding out oil exploration contracts in some of the blocs.

Such actions had "violated China's interests," he added.

Liu was referring to earlier reports quoting Philippine Energy Undersecretary James Layug at the sidelines of an energy forum in Manila on Wednesday.

The reports quoted Layug as saying the Philippines will offer oil exploration contracts for three blocs in the West Philippine Sea on July 31.

All the blocs are off the coast of the western Philippine island of Palawan.

Layug was quoted as saying all reserves in that area belong to the Philippines' exclusive economic zone.

Liu called on the Philippines to make its due contribution to maintaining peace and stability of the area, which China called the South China Sea.

"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," he said.

China also claimed that at the China-Association of Southeast Asian Nations (ASEAN) Foreign Ministers' Meeting in Cambodia this week, 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.

He voiced hopes all parties will do more to enhance mutual trust and promote cooperation for the formulation of a code of conduct in the area.