Sikkim has been cut off from the rest of the country following landslides on NH 31A at Tenth Mile Tarkhola in West Bengal.
Officials said on Tuesday that the landslide occurred at 11 pm last night between Rangpo on Sikkim border and Melli in West Bengal.
Border Road Organisation is trying to clear the debris. It has said that one-way traffic on the highway will be opened by Tuesday evening.
Some traffic to and from the landlocked mountain state is being diverted to the difficult alternative route via Monsong in Kalimpong in Darjeeling district.
The landslide followed heavy rains in north Bengal and Sikkim last week.