The company, which first suspended operations on 11 March as Covid-19 spread around the world, said all agents and passengers with bookings on affected cruises would be contacted directly by Viking’s customer relations team.

Torstein Hagen, Viking’s chairman, said in a letter to customers: “While restrictions related to Covid-19 are beginning to ease in some countries, travel remains complicated.

“Therefore, we have made the decision to extend our temporary suspension of operations through August 31, 2020.”

Viking is offering guests whose cruises have now been cancelled a 125% future cruise voucher with an extra 25% on top of money already paid for the original cruise.

“As a private company, we have the flexibility to do what is best for our guests and our employees,” added Hagen.

“We are committed to maintaining the safest and healthiest fleet in the industry and we are fortunate to have small ocean ships with only 930 guests, and river ships with only 190 guests.

“We have always had the highest standards for health and cleanliness — and are now developing additional protocols to make traveling with Viking even safer.”

Hagen said more information about these protocols would be announced “very soon”.