Story highlights This is the first time Malaysia has blamed North Korea for Kim's murder

Diplomatic relations have soured between the two countries

(CNN) For the first time, Malaysian Prime Minister Najib Razak has directly accused North Korea of murdering Kim Jong Nam.

It comes amid a deepening diplomatic row over the February killing of North Korean leader Kim Jong Un's half-brother at Kuala Lumpur International Airport 2.

"What we are facing now is the result of their action in assassinating their own citizen in Malaysia, on Malaysian soil, using a strictly banned chemical weapon," Najib told state media agency Bernama Wednesday.

A press official for Najib confirmed the comments to CNN. North Korea has repeatedly denied any involvement in Kim Jong Nam's murder.

Kim died on February 13, fewer than 20 minutes after two women wiped his face with the highly toxic VX nerve agent , according to Malaysian police.

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