NEW TAIPEI CITY, TAIWAN - Out under the baking sun, banner-waving protesters shouted "Taiwan, China; One Side, One Country".

With their cries ringing in his ears, a man touted as a future president of Taiwan told a visiting Beijiing official that future cross-strait ties should evolve and proceed on the principle of respecting differences, rather than simply putting them aside while in the pursuit of common interests.

"In the past, we spoke of qiu tong cun yi," said New Taipei City mayor Eric Chu. The saying - to seek common interests and shelve differences - has long used by both Chinese and Taiwanese leaders to diplomatically describe how the former enemies should interact.

Now, it should change, he said. "We should move toward 'qiu tong zun yi'... and respect the Taiwanese people's differing views and choices."

"Qiu tong zun yi" means to respect differences while striving for common goals.

In response, Mr Zhang Zhijun, director of the mainland's Taiwan Affairs Office who was visiting Taiwan's most populous city on Thursday, did not address head-on this point, but stressed that the key to addressing challenges lay in stepping up exchanges.

The remarks by Mr Chu, a darling of the ruling Kuomintang party, carry weight as he is viewed as presidential material and a likely successor to President Ma Ying-jeou come the 2016 election.

Mr Zhang, who is China's first chief of cross-Strait affairs to visit Taiwan, was himself dogged by pro-independence protesters as he moved through the city on Thursday, meeting Taiwanese ranging from businessmen to aborigines who reside in the mountains. At one point, activists beseiged the delegation as it toured the Wulai hotsprings district, before they were taken away by police.