Manila (AsiaNews/Agencies) – The China National Offshore Oil Corporation, Philippine National Oil and Vietnam Oil & Gas have agreed to conduct a seismic survey of the Spratly Islands, a group of 100 reefs and islets located in the South China Sea.

The survey is scheduled to last three years and should determine whether there are any oil and gas reserves in the area, Eduardo Manalac, president of state-owned Philippine National Oil, said.

Mr Manalac said the companies involved, which have already cooperated in the past, were still working out the budget for the pre-exploration activity, but that it would be shared equally. He described the agreement as a purely "commercial transaction that has no reference to political claims or territorial rights".

A spokesman for Filipino President Gloria Macapagal-Arroyo hailed the deal as "a model-setting approach on the South China Sea issue and on forging partnerships on energy security".

The area is claimed by China, Vietnam, Taiwan, the Philippines, Brunei and Malaysia.

Mainland China and Vietnam, both of which have built permanent structures in the Spratlys, clashed over the islands in 1988 and 1992.

Last week, the Philippines and Vietnam announced plans to conduct scientific research in the waters around the islands next month. The move was criticised for not respecting the principles enshrined in the ASEAN declaration on the South China Sea signed two years ago that forbids construction on the islands.