Police vehicles and motorcycle outriders were parked nearby. Senior government officials told AFP that ambassador Kang Chol was expected to leave Malaysia at 18.25 (1025 GMT) on flight MH360 for Beijing, shortly after the deadline for his expulsion expires.
Malaysia and North Korea are enbroiled in an acrimonious dispute over the murder of Kim Jong-Nam, the estranged half-brother of Pyongyang's leader, at Kuala Lumpur International Airport last month.
On Saturday Malaysia declared Kang persona non grata and gave him 48 hours to leave the country after he failed to apologise for his criticism of Malaysia's investigation, which found that Kim had been poisoned with the deadly nerve agent VX.
North Korea has not acknowledged the dead man's identity but has repeatedly disparaged the murder investigation, accusing Malaysia of conniving with its enemies.
Asked by reporters whether he would demand an apology from Pyongyang, Prime Minister Najib Razak replied: "Right now we are not getting anything. I don't expect anything.They should have apologised based on principles, (so) we have declared him persona non grata," he told reporters.
South Korea has blamed the North for the murder, citing what it says was a standing order from leader Kim Jong-Un to kill his exiled half-brother who may have been seen as a potential rival.
The diplomatic dispute erupted last month when Malaysian police rejected North Korean diplomats' demands to hand over Kim's body.
Kang then claimed the investigation was politically motivated and said Kuala Lumpur was conspiring with "hostile forces", referring to the North's arch-rival, Seoul.
Malaysia summoned Kang for a dressing-down, with Najib saying the ambassador's statement was "diplomatically rude".
Malaysia has also recalled its envoy to Pyongyang and cancelled a rare visa-free travel deal with North Korea. It issued a February 28 deadline for an apology.
It ordered the ambassador expelled after he failed to present himself at the foreign ministry when summoned on Saturday.
The foreign ministry has said the expulsion is "part of the process by the Malaysian government to review its relations" with North Korea.
North Korean suspects
Police are seeking seven North Korean suspects in their probe, four of whom left Malaysia on the day of the murder. But on Friday they released the only North Korean they had arrested for lack of evidence.
After Ri Jong-Chol was deported, he claimed police offered him a comfortable life in Malaysia for a false confession, saying the investigation was "a conspiracy to impair the dignity of the Republic (North Korea)".
Two women - one Vietnamese and one Indonesian - have been charged with the actual murder. Airport CCTV footage shows them approaching the heavyset 45-year-old and apparently smearing his face with a cloth.
Police say he suffered a seizure and died less than 20 minutes later. Swabs of the dead man's face revealed traces of the VX nerve agent.
With media camped for a third week outside the North Korean embassy, Kuala Lumpur Monday was buzzing with speculation about would happen if Kang refused to leave.
"He will not be able to hide at the embassy forever. It is better that he surrenders voluntarily... so that he can be sent back," Deputy Home Minister Nur Jazlan was quoted as saying by the New Straits Times newspaper.