Taiwan's President Ma Ying-jeou was sworn in Sunday for a second term, as tens of thousands of demonstrators took to the streets in downtown Taipei to protest his economic policies.

The main opposition Democratic Progressive Party said it expected as many as 100,000 protesters would demonstrate against the president's plans to raise utility prices and allow imports of drug-treated U.S. beef. Media reports put the figure in the tens of thousands.

President Ma, who was first elected in 2008 on a Chinese-friendly platform, had focused in his first term on improving diplomatic and trade ties with China.

Taiwan and China have been separated since 1949, when Mao Zedong's communist forces drove Chiang Kai-shek's nationalists off the mainland. Beijing continues to claim Taiwan as part of its territory, and has vowed to bring the self-ruled island back under China's rule, by force if necessary.