Ukrainian President Volodymyr Zelenskyy said on Wednesday that the environmental harm from Russia's war will affect millions of people for years and urged New Zealand to take leadership in diplomacy to address the damage.

Speaking to the New Zealand parliament - just the second foreign leader to do so - Zelenskyy said by video link from Ukraine that Russian attacks have contaminated the country's oceans and 3 million hectares (7.4 million acres) of forest.

"Dozens of rivers are polluted, hundreds of coal mines are flooded, dozens of the most dangerous enterprises, including chemical ones have been destroyed by Russian strikes," he said, according to translation provided by the parliament.

"All this ... will have a direct impact on millions of people," he said, referring to leaks of hazardous chemicals and contamination from mines and munitions.

"You cannot rebuild the destroyed nature, just as you cannot restore the destroyed lives," Zelenskyy added.

Zelenskyy urged New Zealand, a staunch supporter of Kyiv, to lead efforts at the United Nations and elsewhere to restore Ukraine's environmental security and clear mines.

Now in its 10th month, the war - which Russia calls a "special operation" to demilitarize Ukraine, while Kyiv and its allies call an unprovoked act of conquest - has killed thousands, displaced millions, and turned cities to rubble.

New Zealand Prime Minister Jacinda Ardern on Wednesday announced a further NZ$3 million ($1.94 million) in humanitarian support and told Zelenskyy his was "not a forgotten war."

Since the war began in February, New Zealand, a small Pacific Country of just over five million people, has sanctioned over 1,200 Russian individuals and entities and provided nearly $40 million in assistance.

"Our support for Ukraine is not determined by geography. It is not determined by history or diplomatic ties or relationship," Ardern said. "Our judgment was a simple one: We asked ourselves the question - what if it was us?"