Police have denied assaulting the family of a North Korean citizen who was arrested in connection with the murder of Kim Jong-nam last week.

Inspector-general of police Khalid Abu Bakar said the suspect's family has not lodged any complaint on this.

"That didn't happen. We did not receive any report from the family.

"The accusations are only from the ambassador. Nothing from the family members," Khalid told a press conference today.

"They (the family) cooperated with us well," he added.

North Korean ambassador Kang Chol had on Monday accused Malaysian police of threatening the family of a North Korean citizen and assaulting the latter's son when they raided their condominium in Kuala Lumpur.

Kang also accused Malaysia of trying to pin Jong-nam's murder on North Korea and demanded that North Korea be involved in the investigation.

However, Khalid turned down the request and stressed that North Korea has no jurisdiction to investigate the case.

"No. It is not their jurisdiction (to investigate). It is our jurisdiction," he stressed.

As diplomatic tension between Malaysia and North Korea escalates over Jong-nam's murder, Prime Minister Najib Abdul Razak yesterday described Kang Chol's remarks as being "diplomatically rude" and uncalled for.

Foreign Affairs Minister Anifah Aman also responded on the matter, saying that Kang Chol had issued "lies and half-truths" and that these were insulting to Malaysia.

Jong-nam died on Feb 13 after being smothered with an unidentified chemical by a woman at Kuala Lumpur International Airport 2 (KLIA2).