Malaysian police sealed off the North Korean embassy in Kuala Lumpur to ascertain the number of officials inside, the deputy home minister said on Tuesday, as tensions escalated over the killing of the North Korean leader's estranged half-brother.

"We are trying to physically identify all the embassy staff who are here," deputy home minister Nur Jazlan Mohamed told reporters outside the embassy.

He said staff would not be allowed to leave the embassy "until we are satisfied of their numbers and where they are".

North Korea barred Malaysians from leaving the country on Tuesday, prompting Malaysia to take tit-for-tat action, as police in Kuala Lumpur sought to question up to three men hiding in the North Korean embassy over the murder of Kim Jong Nam.