A group of Taiwanese lawmakers has visited a disputed island chain in the South China Sea to renew Taiwan's claim to the area.

The three ruling party legislators landed Monday on Taiping — the largest land parcel in the Spratly Islands chain.

The Spratlys and surrounding waters are believed to be rich in oil and natural gas reserves. Taiwanese news reports say the legislators were briefed by a small contingent of military personnel already in place.

The visit comes amid rising tensions in the Spratlys — which are also claimed in part or in whole by China, Brunei, the Philippines, Vietnam and Malaysia.

China last month detained 21 Vietnamese fishermen for allegedly violating Beijing's territorial claims to another island chain in the region known as the Paracels. The Vietnamese were released last week, but only after Beijing said they signed pledges “not to infringe on China's maritime rights, especially fishing in its territorial waters.”

The competing maritime claims have also triggered recent faceoffs between Chinese naval and Philippine research vessels, and a series of confrontations elsewhere in the region between fishing trawlers and naval craft from the competing countries.