The Istanbul-Ankara Motorway, connecting Turkey's capital with the country's economic and cultural hub, was partially closed to traffic on Saturday as a landslide blocked the entrance of the Mount Bolu Tunnel.

The landslide, which took place on the northern end of the tunnel, covered all three lanes in the Ankara direction and one lane in the Istanbul direction with earth and rocks through a 50-meter (55-yard) section of the motorway.

The General Directorate of Highways (KGM) said in a statement that the landslide coincided with iftar, the fast-breaking dinner during the Muslim holy month of Ramadan, thus reducing the number of vehicles to a minimum.

No vehicles were stuck in the earth but crews are still searching the area and looking into security footage, it said.

The traffic is expected to return to normal by Sunday noon, the Düzce Governorate said, adding that vehicles were being diverted to the D-100 highway from Abant in the Istanbul direction and from Kaynaşlı in the Ankara direction.

The tunnel is crucial for passenger and freight traffic, bypassing Mount Bolu Pass, itself eponymous with snowfall, accidents and sharp bends.