New Zealand intelligence agencies are reported to have gained evidence that the two Israelis jailed last week for passport fraud were Mossad agents.
The Israelis pleaded guilty but denied they were Mossad agents
According to the New Zealand Herald, the men's communications were bugged after an officer became suspicious.
Prime Minister Helen Clark has refused to comment on the new reports, but she has criticised Israel over the affair.
Meanwhile police have said they are searching for at least one other Israeli in connection with the case.
Assistant Commissioner Jon White told the Associated Press news agency that Zeev William Barkan, 37, and another unnamed man "remain individuals of interest" whom "we are yet to locate".
Last week Ms Clark condemned Israel for breaching New Zealand's sovereignty, after Uriel Zosha Kelman and Eli Cara admitted trying to illegally obtain a New Zealand passport.
The pair were sentenced on Thursday to six months in jail.
Ms Clark said she had "no doubt whatsoever" that the pair were Israeli government agents, and she called on Israel to apologise for its "utterly unacceptable" behaviour.