A senior mainland official on Taiwan affairs on Sunday warned against "increasing risks" and a complex climate in cross-Straits ties in 2018, and urged both sides to continue working together toward peaceful development.

Zhang Zhijun, director of the State Council Taiwan Affairs Office, said in his New Year greeting that 2018 will see increasingly complex changes in cross-Straits ties, as well as new risks and challenges due to "pro-independence" forces in Taiwan.

"The peaceful development of cross-Straits ties is the correct path leading to peace and security for the island, to peaceful unification and benefiting people from both sides," Zhang said in a statement on the office's website.

In the new year, the mainland will continue to uphold the one-China policy and the 1992 Consensus－the fundamental principle of cross-Straits relations whose core is the acknowledgment that the Chinese mainland and Taiwan belong to one and the same China, Zhang said.

However, Taiwan leader Tsai Ing-wen has been refusing to recognize the consensus since assuming office in May 2016 and has turned a blind eye to separatist forces' pursuing their agenda, which in turn has triggered strong opposition from both sides of the Straits, he said.

"Separating Taiwan (from China) will damage national sovereignty, disrupt peaceful development of cross-Straits ties, undermine peace and security on the island, and will only bring disaster to people on both sides, particularly the Taiwan people," Zhang said.

"We will resolutely oppose separation through legal means, as well as subtle and gradual attempts of separation that try to erode the foundation of peaceful unification," he said.

Only when the current Taiwan authority acknowledges the 1992 Consensus can both sides begin dialogue without obstacles and work together to solve issues of common concern, he added.

As for people to people exchanges, Zhang said the mainland will continue to deepen its economic and social integration and cooperation with Taiwan, and encourage Taiwan residents to study, work, innovate and live on the mainland.

Chen Deming, president of the Association for Relations Across the Taiwan Straits, said on Sunday in his New Year greeting that due to the damage to the 1992 Consensus, the consultation mechanism between his association and the Taiwan-based Straits Exchange Foundation has been suspended.

But the association actively facilitated civil exchanges between the two sides last year, and Chen said that cross-Straits ties will witness a new chapter of peaceful development through the joint efforts of both sides.