Pakistan has joined the growing list of countries taking action against open-loop scrubbers.

The country has barred the discharge of wash-water from the exhaust-cleaning systems in the port of Karachi.

This is according to a circular issued by the ports and shipping department of the Ministry of Maritime Affairs.

UK insurer Standard Club warned its members: "While in the port, vessels fitted with hybrid type of scrubbers should switch to the closed-loop mode of operations.