BEIJING, April 11 (Xinhua) -- The Chinese mainland has warned Taiwanese authorities that "courting foreign support to build you up will only invite trouble," according to a mainland spokesperson Wednesday.

"The Taiwan issue concerns China's sovereignty, territorial integrity and the national feelings of the Chinese people," Ma Xiaoguang, spokesman for the State Council Taiwan Affairs Office, said at a press conference.

"We will never waver in safeguarding China's core interests," Ma said.

Asked about American officials' possible visit to Taiwan and the U.S. Department of State's approval of a marketing license for selling military submarine technology to Taiwan, Ma urged the United States to abide by the one-China principle and the principles of the three Sino-U.S. Joint Communiques.

Any outside forces that attempt to "play the Taiwan card" will find their efforts "futile" and will hurt themselves if they get "over the line," he said.

Asked about Taiwan's response to Sino-U.S. trade disputes, Ma said a few people in Taiwan wanted to take advantage of the disputes to do things that were "not upright," and have lifted a stone that will "smash their own feet."

"Returning to the right track of the '1992 Consensus' and the peaceful development of cross-Strait relations is the only way Taiwan can avoid becoming a pawn of others," he said.

Ma also hailed the benefits of cross-Strait economic cooperation, promising that a more open mainland would create new opportunities for Taiwanese compatriots and businesses.

"Anyone who wants to hinder cross-Strait economic cooperation will fail," he said.