A spark in the third rail at Tollygunge station disrupted Metro Railway services for over half an hour in the city Tuesday, an official said.
The Metro Railway, which has been affected by frequent technical snags of late, was witness to another disruption from 2.21 pm when a spark was noticed in the third rail which carries electrical power to the trains.
The snag was attended to and services were restored at 2.56 pm, Metro spokesperson Indrani Banerjee said.
The last disruption in Metro was on February 13 due to a breakdown in power supply to a Kavi Subhash-bound rake at Dum Dum station.
Prior to that, smoke emanated from under a train near Dum Dum station and entered a few compartments, causing complaints of suffocation by three passengers on January 31.
Passengers had to be evacuated and they walked to the platform of the station.
On December 27, smoke was detected in a coach of a train between Maidan and Rabindra Sadan stations and hundreds of panic-stricken passengers had to be evacuated through the tunnel of the underground carriage system.
The Kolkata Metro, the oldest underground railway system in the country, started its services in 1984.