Addressing a rally at Udaipur in Lahaul-Spiti district, he said the construction of 3.5-km of the tunnel has been completed.
The project will be speeded up to ensure that it is completed at the earliest.
The 8.9-km long tunnel will reduce the distance between Manali and Keylong by 55-km and provide an all weather road to tribal Lahaul and Pangi valleys.
He said the construction of tunnels from Tissa to Killar and Karsehar to Telang would be taken up with multi-lateral funding agencies.