Kolkata, Feb 2 : Three workers engaged in scavenging and manual cleaning of a sewerage drain pipe within Bantala leather complex on eastern outskirts of Kolkata died on Sunday morning.

However, at the time the report was filed, there was confusion about the exact reason behind their death.

The police are not ruling out any of the two possibilities, drowning in the wastewater accumulated at the sewerage drain pipe or inhaling poisonous gas in the sewage.

However, the real reason behind the death would be known only after the bodies are recovered and thereafter the post-mortem of their bodies is being conducted.

The three workers killed in the incident are Suman Sardar, Hasi Seikh and Forjem Sheikh.

Kolkata Municipal Corporation (KMC), under whose jurisdiction the said sewerage drain pipe comes, has not commented on the incident yet.

Tension prevailed in the area where the incident occurred.

Incidentally, last week only a bench of the Supreme Court led by Justice Sudhanshu Dhulia had ordered a complete ban on manual scavenging and sewage cleaning in six major metropolitan cities including Kolkata.

The other five cities, where the same ban would be applicable as per the Apex Court order, are Mumbai, Delhi, Bengaluru, Chennai and Hyderabad.

The Apex Court directed the heads of the municipal bodies in these cities to file an affidavit at the apex court by February 13, explaining the steps taken to stop this practice and how and when the system has been completely stopped in respective cities.

The next hearing is scheduled for February 19.

Recently, during a discussion held by the National Human Rights Commission (NHRC) on the rights of manual scavengers and ensuring their dignity, experts suggested that robots can be used to clean sewage lines and septic tanks.

Addressing the discussion on 'Dignity and Liberty of the Individuals -- Rights of Manual Scavengers', NHRC Chairperson, Justice V. Ramasubramanian said it is necessary to study and understand the causes to suggest remedial measures.

/IANS