PM Jacinda Ardern is expecting a response over whether to proceed with a proposed Russian travel ban soon.

New Zealand has imposed a travel ban on the Russians expelled by other allied nations, following the nerve agent attack on a former Russian double-agent and his daughter in the UK.

Several nations, including every other Five Eyes partner, have expelled a number of Russian diplomats following the attack.

The ban applies to the diplomats expelled by our Five Eyes partners and other close allies, affecting at least 100 Russian nationals.

GETTY IMAGES Winston Peters says it would be naive to believe there was no intelligence gathering by Russians in New Zealand.

Prime Minister Jacinda Ardern announced the ban on Thursday evening.

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"We will be asking our security partners to provide those names to us," Ardern said.

"Those names will then be placed on a travel ban list to ensure that individuals who have been found to undertake activities incompatible with their diplomatic status in other countries do not enter New Zealand."

On Thursday, Foreign Minister Winston Peters spoke to the British High Commissioner Laura Clarke about the Salisbury attack and New Zealand's response.

But Peters continued to refuse to blame Russia for the attack, saying the nerve agent was made in, and came from, Russia but the UK investigation was yet to establish who was responsible. Other countries, including the UK, had pinned the attack on Russia, and Ardern said there was no other plausible explanation for who was responsible.

The measure is similar to those imposed against specific Russians and Ukrainians by former foreign minister Murray McCully in 2014, after Russia annexed Crimea from Ukraine.

At the time, McCully said the sanctions would apply to about 20 people.

The travel sanctions come after the attack on a former Russian spy Sergei Skripal and his daughter in Salisbury earlier this month, with the use of a banned nerve agent manufactured in, and transported from, Russia.

Ardern said the only plausible explanation was the attack was carried out by Russia. Meanwhile, Foreign Minister Winston Peters said further investigation was needed to confirm who was responsible for, and carried out, the attack.

Both Ardern and Peters were quick to condemn the attack and the use of the banned chemical. However, New Zealand did not follow its international partners in expelling Russians who were gathering intelligence on New Zealand soil.

So far, Russian diplomats have been kicked out of more than 20 countries, including 18 European Union states, the US and Canada.

New Zealand has faced criticism locally, and internationally, for not taking the same action.

But Ardern and Peters maintain New Zealand did not have any Russian intelligence agents who met the criteria for expulsion, however, they continued to monitor the situation, and manage any threats.

The agents kicked out of other countries were "undeclared intelligence agents", Ardern said, adding that the New Zealand Security Intelligence Service (SIS) and New Zealand's Five Eyes partners were consulted, and agreed there was no one who fitthat criteria in New Zealand.

Peters and Ardern said that did not mean there were no Russians gathering intelligence in New Zealand.

"To say that that there's no intelligence from [diplomats at the embassy] or other sources, would be naive," Peters said.

The SIS was aware of Russian intelligence activity here and "where it is seen appropriate, action is taken", he said.

But Peters, and the minister in charge of the SIS - Andrew Little - would not elaborate on the type of intelligence activity, how many people were being monitored, or what type of action had been taken.

Since the Salisbury attack, the Russian Ambassador had been summoned by the Government to talk about the ongoing issues.

Welcoming the new @UKinNZ British High Commissioner @LauraClarkeUK to #NZ at her introductory meeting this morning pic.twitter.com/kyW2xkc8nJ — Winston Peters (@winstonpeters) March 28, 2018

And on Thursday morning, Peters also discussed the situation with British High Commissioner Laura Clarke during a pre-arranged introductory meeting.

The pair discussed a range of issues, including Russia and Eastern Europe," Peters said.

"[It was] really a canvassing of everything that happened since Salisbury and before."

Clarke "understood entirely" New Zealand's response to the Salisbury attack," he said.