There is no solid evidence to show that China is trying to undermine Taiwan's diplomatic ties with Palau, but government agencies will continue keeping a close watch on related developments, Foreign Minister Timothy C. T. Yang said Thursday. Fielding questions from opposition Democratic Progressive Party (DPP) lawmaker Chen Ying at a legislative session, Yang said his ministry and the National Security Bureau (NSB) will keep monitoring ensuing developments between the two countries, as a Chinese petroleum company, through a regional agent, has signed a US$40 million cooperation plan with Palau to help the South Pacific nation exploit oil reserves. Noting that China often uses economic cooperation ventures to cement ties with other countries, Chen warned the government of possible changes in the Taiwan- Palau formal diplomatic links. Yen Mong-han, deputy director-general of the NSB, said that apart from the oil venture, no solid evidence has been detected that Beijing is plotting to spoil Taiwan's diplomatic relations with Palau. Palau is one of the 23 countries that maintain full diplomatic ties with Taiwan. Most of these countries are in the South Pacific, Africa and Latin America. 