Malaysia has rescinded visa-free entry for North Koreans, citing the move as a security measure amid a diplomatic spat over the murder of Mr Kim Jong Nam, half-brother of North Korean leader Kim Jong Un.

"Beginning Monday, all North Koreans who want to come to Malaysia will need a visa," Deputy Prime Minister Ahmad Zahid Hamidi told reporters yesterday.

Pyongyang has criticised Kuala Lumpur's handling of the investigation and rejected autopsy findings that Mr Kim was killed using a lethal nerve agent, VX, on Feb 13.

Datuk Seri Zahid yesterday also warned the North against resorting to such "antics" to push its agenda.

In 2000, Malaysia granted North Koreans visa-free access to the country. Malaysia practises a "neutral" foreign policy, which includes engaging countries regardless of its beliefs. Ties with North Korea began in the 1970s as part of Pyongyang's wider reach to the developing world.

In 2009, Malaysia became the first country whose citizens did not need a visa to travel to North Korea.

Bilateral ties have been strained since Mr Kim's death, with North Korean officials accusing Malaysia repeatedly of colluding with foreign powers against their country.

"We don't want to make enemies, but they have used Malaysia as a site to interpret their own agenda," Mr Zahid said yesterday.

Malaysian police are looking for seven North Koreans, four of whom are believed to have fled back to Pyongyang.

One of the other three is a North Korean Embassy official in Kuala Lumpur who is wanted to help in investigations.

Observers say the North's war of words will only do it more harm at a time when it is facing tough sanctions over its missile tests.

"If they continue to stonewall in terms of production of material witnesses Malaysia wants, and also in making outlandish accusations, there is scarcely any loss on Malaysia's part in terms of severing ties," said Mr Oh Ei Sun, a senior fellow at the S. Rajaratnam School of International Studies.

"Malaysia does not want to escalate such tension. But the same could not be said about North Korea," he added.