Taiwan has relaxed controls on visits to the Chinese mainland by middle and lower ranking civil servants and police, amid expanding cross-strait exchanges, an official has said.

A rule decreeing government employees visit the mainland only for family reunions was removed Thursday, but they would be required to travel in groups.

It would be forbidden for the visitors to engage in activities that could damage "'national security and national interests'", or become involved in political affairs, or form alliances with mainland people, organizations or government units, a Taiwanese official said.

The relaxation does not apply to top-level government officials and police officers, who are still barred from visiting the mainland for any reason.

Civil exchanges between Taiwan and the mainland resumed in late 1987, after then Taiwanese "president" Chiang Ching-kuo lifted a four-decade-old ban to allow family reunion trips to the mainland.

Commercial ties betwee the two sides have also since expanded, with mainland becoming the island's largest market and favoured destination for Taiwanese investors.

A total of 4.1 million Taiwanese, including 6,453 civil servants and policemen, visited mainland in 2005.