The BRO personnel reopened the Jawaharlal Nehru Road, which connects Gangtok to Nathu La, after they worked round-the-clock to clear the boulders.
The reopening of the road enabled the around 4,000 stranded tourists in 417 vehicles to return Gangtok safely, they said.
Landslides triggered by showers had snapped the road link between Gangtok and Tsomgo lake yesterday near 15 Mile, en route to Tsomgo lake and Nathu La in Sikkim.
The stranded tourists from all over the country on way to the Tsomgo lake and Nathu La were provided shelter and food by by the Army at their bases beyond 15 Mile yesterday.
Yesterday, was the first day of the week when Nathu La was opened to tourists as traffic upto the Indo-China border remains closed on Mondays and Tuesdays.
Lukendra Rasaily, president of Travel Agents Association of Sikkim (TAAS), told PTI the boulders started falling on the road after 2 PM yesterday and at around 4 PM it got totally blocked after another landslide struck above 15 Mile.
Rasaily also said all the tourists have returned safely to Gangtok after the road was reopened.