The Kerala government on Wednesday suspended construction of the Wayanad twin tunnel project following a landslide at the construction site that killed three migrant workers and left five others missing.
Search operations are continuing for the missing workers.
After a Cabinet meeting, Chief Minister V D Satheesan said the government would conduct legal and technical investigations into the incident and review all vulnerable factors before allowing construction to resume.
He said the Union government had laid down strict conditions while granting environmental clearance for the project and that authorities would examine whether the construction company had complied with those directives.
"Work will resume only after evaluating all vulnerable factors," he said.
The chief minister said there would be two separate inquiries. One would determine the cause of the tragedy, while the other would examine whether the Centre's environmental and safety guidelines had been followed.
Satheesan later left for Wayanad to assess the situation.
The Rs 2,400-crore project is being implemented by the Konkan Railway Corporation. Dilip Buildcon is constructing the twin tunnels, while Royal Construct is responsible for the approach roads and bridges.
Construction began last year from both ends of the project, at Meppadi in Wayanad district and Anakkampoyil in Kozhikode district.
The proposed 8.2-km tunnel will pass through the ecologically fragile and landslide-prone Western Ghats and is intended to improve connectivity between Wayanad, Karnataka, and other parts of Kerala.
Construction has progressed on the Kozhikode side, where one tunnel has crossed the 50-metre mark. On the Wayanad side, work has so far been limited to preparing the tunnel entrance through slope benching.