The ship operators, including Costa Cruises, MSC Cruises, Royal Carribean Cruises and Ponant, signed the “Blue Charter” agreement in Marseille, Reuters reported.

The four signatories transport 95% of the passengers and account for 85% of the stopovers in Marseille.

The Port of Marseille Fos is France’s number one cruise ship port and the fourth-biggest in the Mediterranean, with 1.75 million passengers last year and a target of 2 million in 2020.

The move comes in line with the upcoming implementation of the IMO's 2020 sulphur cap, which will require all ocean-going ships to reduce the sulphur content in fuels used in their vessels from 1st January.

Although cruise industry is a vital component of Marseille's economy, air pollution from cruise ships has been a main area of concern by local residents’ associations for years.

According to official local data, fumes emitted by cruise ship chimneys are responsible for 40% of the area’s nitrogen oxide emissions, 32% of the sulfur dioxide emissions and 15% of its particulate matter pollution.

A study by Transport & Environment in June revealed that 57 cruise ships in Marseille emitted in 2017 almost as much NOx as one-quarter of the city’s 340,000 passenger cars.

At the end of 2017, the Port of Marseille Fos established a working group, attempting to reduce the impact of ships in the Port and find ways to develop LNG as a marine fuel.

Last month, the port also revealed plans to spend €20 million over the next six years to extend shore power connections for berthed vessels to every ferry, cruise ship and repair quay within the Marseille eastern harbour.

Last month, Cannes, France’s fourth-biggest cruise ship port, said it would ban the most-polluting cruise ships from next year in an attempt to boost air quality in the city.