Malaysian police investigating the murder of Kim Jong-nam say attempts were made to break into the morgue where his body is being held and have demanded to question a senior North Korean diplomat.

The announcements by police chief Khalid Abu Bakar throw further suspicion on Pyongyang over the apparent assassination of the exiled half-brother of the North Korean dictator, Kim Jong-un.

Khalid said another man wanted for questioning and identified as Kim Uk-il was linked to North Korea’s state airline, Air Koryo. Both he and the high-level embassy official, named as Hyon Kwang-song, 44, remained in Malaysia, Khalid said.

“He’s the second secretary of the embassy … They’re not in custody; they’ve been called in for assistance,” Khalid told journalists at a press conference.

“We knew there were attempts by someone to break into the hospital mortuary. We had to take precautions. We will not allow anyone to tamper with the mortuary,” the Malay Mail quoted him as saying.

He added that investigators knew who had made the attempted break-in but that there was “no need for me to tell you”.

Kim Jong-nam, who lived most of his life outside his home country, died from a seizure en route to hospital nine days ago after complaining that a woman had sprayed chemicals on his face at Kuala Lumpur international airport.