KOTA KINABALU (THE STAR/ASIA NEWS NETWORK) - Malaysia's decision to expel North Korean Ambassador Kang Chol was aimed at upholding the nation's integrity and sending a strong and clear message to the North Korean government not to meddle in investigations into the Kim Jong Nam murder, Deputy Prime Minister Ahmad Zahid Hamidi said on Sunday (March 5).

"The statements by the ambassador were obviously aimed at manipulating the matter," Dr Ahmad Zahid, who is also the Home Minister as well as Umno deputy president, said after meeting party leaders and members.

He said Malaysian authorities had carried out painstaking investigations into the Feb 13 assassination of Kim, the estranged half-brother of North Korean leader Kim Jong Un, at Kuala Lumpur International Airport.

Malaysia has been accused by the North's envoy to the country, Mr Kang Chol, as "colluding" with South Korea in its investigation into the killing.

On Saturday, Wisma Putra informed the North Korean Embassy that Mr Kang must leave Malaysia by 6pm on Monday. The move came after North Korea failed to offer a written apology for Mr Kang's accusations by Feb 28,Foreign Minister Datuk Seri Anifah Aman said in a statement.

The ambassador also failed to respond to a summon to Wisma Putra on Saturday.

"We have been professional in our probe in terms of interviewing witnesses and collecting evidence, whether it was DNA samples or CCTV footage," said Dr Ahmad Zahid.

On March 1, Vietnamese Doan Thi Huong and Indonesian Siti Aisyah were charged with Jong Nam's murder. Neither women recorded a plea, and April 13 has been fixed for mention.

North Korea's strident criticism of Malaysia's handling of the case has sparked a diplomatic row between the two countries.

On March 2, Malaysian announced that North Koreans would no longer enjoy visa-free travel to Malaysia from March 6 onwards.