Immigration New Zealand believes only one agent is responsible for all 279 fraudulent student visas issued from its Beijing office. The agency discovered the fraud earlier this year.
Immigration NZ head Steve Stuart is currently in China visiting the department's Shanghai and Beijing offices.
He says investigators have found the fraudulent documents, which were all likely to have been submitted to its Beijing office, by one immigration agent.
Mr Stuart says the man's motivations for committing the fraud are not yet known and he has refused to be interviewed.
He is to meet Chinese authorities this week to discuss what action they may take against the agent.
Mr Stuart says students interviewed by investigators in New Zealand say they were unaware the agent was using false documents in their applications.
He says decisions on whether to deport the 230 students still in New Zealand on fraudulent visas will be made on an individual basis.