Cruise-selling agents have been repeatedly urged to boost their sustainability knowledge within the sector as lines increasingly turn to cleaner fuels.

Twenty-six of the 88 crusie ships coming into service over the next six years will use the cleanest fossil fuel available – liquefied natural gas (LNG), Clia chairman Tony Roberts said.

Speaking at Abta’s New Markets In Cruise Conference on Wednesday, Roberts said customers who have concerns about how green the cruise industry must be told the facts by agents.

He said: “People are going to be asking about this more and more – and I am not suggesting that the whole industry is squeaky clean – but there are huge steps are at the heart of what we do as an industry.”

According to Roberts, $22 billion is being invested by Clia member cruise lines in new green energy technologies.

P&O Cruises’ new ship Iona will be the first in the UK to be powered by LNG when it enters service next year.

More: Thomas Cook collapse will see increase in homeworkers’

 MSC Cruises to offer dynamic packaging tool

“The industry is investing a huge amount to ensure that we are operating in a sustainable way,” added Roberts, Princess Cruises’ UK and Europe vice president.

Geir Kronbæck, Royal Caribbean International’s Nordics general manager, went one step further and warned the industry that it could “be caught with its pants down” by younger cruisers if it did not engage with agents over sustainability.

The International Maritime Organisation’s new emission standards come into effect from January 1 to all but eliminate sulphur emissions.

As a result, Royal Caribbean will launch its first Icon-class ship in 2022 which will be powered by LNG combined with hydrogen fuel cells.

Kronbæck said: “Without the ocean we do not have a business to run. What we do have is a communication problem, an education problem and we have been hiding under our desks not talking about what we do.

“Several times companies who tried to say that they are green have been caught with their pants down,” he said.

“If we do not engage with travel agents about what we do, the young ones will figure us out and catch us with our pants down.”