A senior Taiwanese official on mainland affairs said Wednesday that Zhang Zhijun, the Chinese mainland\'s newly appointed Taiwan affairs chief, is welcome to visit the island at a proper time.The continuous development of cross-Strait relations and enhanced exchanges between the mainland and Taiwan will promote mutual prosperity, Wang Yu-chi, mainland affairs chief for the Taiwan authorities, said at a press conference.Zhang, born in 1953, previously served as the mainland\'s vice foreign minister. He replaced Wang Yi as director of the State Council\'s Taiwan Affairs Office.