Zhang, who was visiting at the invitation of the Taiwan National University of the Arts as dean of journalism at Xiamen University, was shoved to the ground by a mob allegedly incited by Wang Ting-yu, a local lawmaker from Taiwan's Democratic Progressive Party (DPP).
The ARATS has condemned the violence and asked the Taiwan authority to prevent such incidents in future.
Yang said security measures for Chen's stay should "refer to" the measures for Chiang when he was visiting mainland, Yang said, without giving details.
He also said Zhang, who cut short his Taiwan tour after the incident, was still receiving medical treatment in Beijing.
Asked to comment reports that lawmaker Wang was under threat of violence to apologize, Yang said the story was "a lie full of loopholes and contradictions".
Taiwan media reported that Wang claimed that he was threatened at gunpoint by a local businessman Huang Ju-yi to apologise in public for the incident involving Zhang. But Huang told police that he had known Wang for many years and he did not threaten Wang, nor did anything illegal.
Yang said the lie was fabricated and spread by a very few people on the eve of Chen's visit to Taiwan. "It has clear political motives," he said, adding that he believed the lie would not easily fool the Taiwan public.
(Xinhua News Agency October 29, 2008)