Wellington, Sep 16 (IANS): New Zealand Prime Minister John Key came under renewed pressure Tuesday to explain the extent of government surveillance of the public following claims by US spy whistleblower Edward Snowden that mass surveillance was already in place.

Key has been accused of obfuscating the issue by declassifying government documents on a cyber security programme called Cortex, while consistently refusing to discuss claims that New Zealand's Government Communications Security Bureau (GCSB) was using a US National Security Agency (NSA) surveillance tool known as XKeyscore.

At a public meeting in Auckland Monday, Snowden said in a video link from Russia that the NSA had two facilities in New Zealand and that data supplied by the GCSB was being shared with partners in the "Five Eyes" spying network in the US, Britain, Canada and Australia.

Key told Radio New Zealand Tuesday that he stood by his denials that there was no mass surveillance or mass collection of New Zealanders' communications data, Xinhua reported.

Key said he had checked the claim of NSA bases operating in New Zealand, and to his knowledge it was not true, although NSA staff might be seconded to local bases.

He again refused to discuss XKeyscore, and countered that Snowden and Pulitzer Prize-winning journalist Glenn Greenwalk, who spoke at the meeting, had no evidence to support claims of mass surveillance.

"What we're seeing in this whole debate is a bunch of foreigners coming into town three or four days before an election at a time when New Zealanders want to have a legitimate debate about the future of our country and what they're doing is making completely unsubstantiated claims," he told Radio New Zealand.

Greenwald used NSA documents obtained from Snowden to show the GCSB had proceeded with implementing a surveillance programme called "Speargun".

Key, who has admitted that the GCSB had abandoned proposals for mass surveillance, said the NSA documents actually referred to a mass cyber-protection mechanism called "Cortex".

The main opposition Labour Party said Key was being evasive and still had serious questions to answer just days before a general election Sep 20.

"The issues raised last night are extremely important to matters of privacy. New Zealanders deserve answers and they need them before the election," Labour leader David Cunliffe said in a statement.