Heavy rains brought down tonnes of water, mud and tree trunks onto a part of the main highway linking capital Kuala Lumpur to Kuantan in Pahang yesterday evening, with media reports saying at least four cars were trapped in the landslide.
There were no reports of casualties at press time.
The 6.45pm landslide occurred along Karak highway not far from the Bukit Tinggi area, which is several kilometres away from the exit road to Malaysia's most visited destination of Genting Highlands, the reports said.
A spokesman for the Pahang Fire and Rescue Department told The Straits Times that the landslide was "quite a distance away" from the Genting road, so those coming down from the Genting resorts heading back to Kuala Lumpur were not affected.
The authorities closed all four lanes near the 52.4km marker of the highway at Bukit Tinggi, as excavators and rescue staff worked to clear the debris and carry out rescue work.
The Karak highway winds up and down mountains, and is the main road taken by most motorists to drive from KL to Kuantan and other parts of the east coast states.
A one-way trip between KL and Kuantan takes about three hours.
The highway closure caused traffic snarls several kilometres long. Police told motorists to take detours dozens of kilometres away, or to postpone their trips.
The Malaysian Highway Authority said on its Twitter posting: "All lanes are blocked, traffic at standstill. Postpone your journey."
The landslide occurred at the KM52.4 marker of the expressway, it added.
Pictures posted on social media by those caught near the landslide showed mud water, fallen tree trunks and cars stuck along the highway in the dark.
One picture showed an MPV beside a road divider after apparently being struck by fallen tree branches, while another showed a big lorry stuck at the side of the road.
The Pahang Fire Department spokesman said that although a lorry, two cars and two four-wheel drives were buried in the mud, their drivers and passengers had managed to escape to safety.
"We are still looking, however, to ensure there are no trapped victims," he said.
Bentong district police chief Mansor Mohd Nor told The Star newspaper that there were no reports of loss of life so far.
The New Straits Times newspaper quoted a Works Ministry statement as saying that machines clearing the road at the landslide area were working in the heavy downpour.
"It is still raining heavily at the location, and care has to be taken as there may be more soil movement," the ministry said.
Prime Minister Najib Razak in several Twitter posts expressed concern for the safety of the road users.
"I was made to understand that there are a few vehicles buried by a landslide on the Karak highway. Rescue work must be carried out immediately.
"I hope other road users near the scene are safe. Please be calm while the authorities clear traffic. Obey their orders," he said.