Military personnel in Salisbury amid the probe into the nerve agent attack (Andrew Matthews/AP)

New Zealand has put aside plans to pursue a free trade deal with Russia and joined other nations in condemning the country following the poisoning of a former spy in Britain.

New Zealand had come under increasing pressure from allies to denounce Russia following the nerve agent attack on Sergei Skripal and his daughter Yulia in Salisbury.

Leaders finally did that when Prime Minister Jacinda Ardern and foreign minister Winston Peters said in a joint statement there was no plausible explanation other than the poison came from Russia.

“The Russian reaction has been cynical, sarcastic and inadequate,” they said.

A spokesman for Ms Ardern said plans to pursue a free trade deal were on hold following the Salisbury attack.

New Zealand first started negotiating a deal with Russia, Belarus and Kazakhstan in 2010 in hopes of getting better access for butter and beef exports. Negotiations were suspended in 2014 after Russia annexed Crimea.

But Mr Peters had been pushing to progress the deal again. In an interview with Newshub last week before the attack in Britain, he said he was “deadly serious” about pursuing a Russia trade deal, and that there was no evidence Russia had been responsible for shooting down a passenger plane over Ukraine.

After the British attack, Mr Peters put out a statement expressing concern and saying the question of how the nerve agent got to Britain from Russia was the “key issue”.

Many considered that statement to be unconvincing.

Opposition politician Todd McClay said Mr Peters was earning a reputation as a Russia apologist and that New Zealand needed to stand by the UK.

Laura Clarke, the British High Commissioner, told Radio New Zealand there could be “compatibility” issues should New Zealand continue to seek trade deals with Russia as well as the European Union and Britain.

On Friday the government took a much tougher stance.

“New Zealand fully supports the sovereign right of the UK to take the action it considers appropriate in response to this violation of international law on its territory,” Ms Ardern and Mr Peters said.

PA Media