Cross-straits romance is the main cause of Chinese mainland tourists staying in Taiwan illegally, the Taiwan interior department said.

Taiwan opened the door to individual tourists from the mainland cities of Beijing, Shanghai and Xiamen in 2011 and extended permission to residents of 10 more mainland cities in 2012.

By the end of November, a record 1 million individual tourists from the Chinese mainland had visited Taiwan this year, Chen Chun-ching, vice-minister of Taiwan's interior department, was quoted by the Central News Agency.

"Eighty-four people have illegally stayed in Taiwan, 52 of whom have not yet left and their whereabouts are unknown," Chen was quoted by the Taiwan news agency.

An investigation found most of the 52 remained in Taiwan because they have girlfriends or boyfriends there, Chen said.

Chen Xiancai, a Taiwan studies scholar at Xiamen University, said that as exchanges become more frequent, Taiwan-related departments should speed up the pace in adjusting policies to attract mainland tourists and protecting the rights of Chinese mainland spouses in Taiwan.

Since the first cross-Straits marriage was registered in Xiamen, Fujian province, in 1989, the number of such marriages registered on the Chinese mainland had soared to more than 350,000 by the end of 2013.

Chen Xiancai, the Xiamen University professor, said that most cross-Straits romances start with communication on the Internet or phone, through introductions of relatives or friends, or during visits to Taiwan or the Chinese mainland.

However, once a relationship develops into a marriage, the couple usually run into problems with Taiwan IDs.

About 400,000 people in Taiwan have spouses from the mainland, but more than half of those spouses lack Taiwan identity cards, complicating their lives. The spouses have asked Taiwan authorities to reduce the current waiting period from six years to four - a request that has not been acted upon.

hena@chinadaily.com.cn