"Because at that University they were teaching spies - but he also was a student - logically, he was a spy," Chen said.
"We're very happy seeing these reports disclosing these connections. The community is thinking this should have been understood earlier."
Yang's response to Herald questions yesterday was the solitary line: "Mr Chen's allegations are false."
Since a press conference given after news of his military intelligence background broke in September, the embattled MP has not spoken with English-language media.
Chen said Yang played a "very active" role in New Zealand Chinese community events where he exhorted the local community to follow the party line.
"He said that as Chinese immigrants we have heritage from China and we should follow those directives instead of New Zealand values," he said.
"Some participants thought he's more of an ambassador for the embassy and not for the National Party."
Chen said he was unable to return to China due to his work with the pro-democracy movement, and until recently was visited annually by Security Intelligence Service officers.
"They wanted to know two things. One is about my personal safety, and the second thing is my information about potential Chinese spies in NZ," he said.
Chen said Yang was not discussed during these visits,
But Yang was a subject of discussion at parliament this week, as fallout rained from a Herald report that the MP had in 2012 lobbied for someone seeking a sensitive defence force job who had been denied clearance by the SIS.
New Zealand First leader Winston Peters has urged an investigation into the lobbying claim. Yang has described the applicant as a constituent. The MP said he did no more than seeking answers on the constituent's behalf through the appropriate channels.
National leader Bill English has defended his MP's handling of the episode and said claims Yang lobbied to overturn a security classification was "overstretching it".
"He's dealt with a concern from a constituent in a way that any MP is virtually obliged to," he said.