Five Philippine lawmakers flew to a disputed South China Sea island Wednesday in an action China had warned would “sabotage” relations between the two countries.

The legislators, including two members of President Benigno Aquino's party, said the trip was intended to assert Philippine sovereignty in a section of the potentially oil- and gas-rich Spratly Islands.

A reporter who accompanied the group said they were greeted on the tiny island by Philippine soldiers and villagers, who joined them in raising a flag and singing the national anthem.

The Chinese embassy in Manila had criticized plans for the trip Tuesday, saying it would serve “no purpose but to undermine peace and stability in the region and sabotage the China-Philippines relationship.”

Tensions between the countries have been raised by several incidents in which Philippine fishermen and oil exploration vessels were harassed by Chinese vessels in waters claimed by Manila as part of its exclusive economic zone. In response, Philippine officials have begun referring to the area as the West Philippine Sea.

The Chinese embassy statement said the lawmaker's action violated the spirit of a 2002 declaration in which China and members of the Association of Southeast Asian Nations agreed to work toward negotiating a binding code of conduct to govern territorial disputes in the sea.

Chinese and ASEAN officials announced Wednesday in Bali, Indonesia, they had agreed on guidelines for moving ahead with those negotiations. China, Taiwan and four ASEAN members hold overlapping territorial claims in the South China Sea.