Two labourers died after inhaling poisonous gas while cleaning a sewage tank in the Chowkaghat area here on Saturday, police said.
Sewage tanks in the area are being linked with pumping stations of the Dinapur sewage treatment plant, which Prime Minister Narendra Modi is scheduled to inaugurate on November 12 during his visit to Varanasi, they said.
The newly-constructed sewage treatment plant was being made operational ahead of the prime minister's visit, for which more than a dozen labourers were engaged in the cleaning of sewage lines, police said.
A team of the National Disaster Response Force (NDRF) was rushed to the spot and fished out the bodies of two labourers. They were identified as Vikas Paswan (18) and Dinesh Paswan(27), natives of Bhabhua in Bihar.
A junior official at the Uttar Pradesh Jal Nigam was taken into police custody for allegedly sending the labourers inside the sewage tank without safety equipment, police said.
A probe into the matter was underway, they added.