The claim comes a day after the Aberdeen-Orkney-Shetland operator said it had closed its bars and shops because of the coronavirus pandemic.
But a crew member aboard one of the vessels said: “I would like to inform you that although the bar is closed, the shop is still opening for passenger use, although on restricted hours, and there is still alcohol available to passengers.
“Despite the fact it is unnecessary and would, in my opinion, make passenger less likely to comply with government instructions and recommendations with regards to social distancing."
NorthLink said the shops were now closed and only opened up when individual passengers requested specific items such as painkillers or toiletries.
A spokesperson said beer and wine were still being served, but only in the restaurant, which was also only open for one hour.
Passengers were being served at tables to prevent them coming too close to each other at counters.
NorthLink said yesterday that on-board cinemas had also been closed and food would continue to be served but with “stricter enforcing of social distance requirements”.
The Rail, Maritime and Transport union, which represents many of the crew, said it had raised the issue with the Scottish Government.
CalMac, which operates west coast ferries, ended its on-board catering on Saturday night.
Another source had told The Scotsman yesterday: "NorthLink ferries have had their bars and restaurants open all weekend.
“There are no social distancing measures in place.
“Passengers are free to go in the Magnus Lounge, shop, restaurant etc.
“Passengers free to roam around the ship, play on the gaming machines. Vending machines on as well.
“Crew are terrified.
“The ferries are an absolutely perfect environment to spread the virus – hundreds of people in an enclosed environment, repeatedly touching the same surfaces.
However, the Serco-run operator insisted it had followed official advice.
Managing director Stuart Garrett said: “The well-being of our passengers and staff is always our top priority, and since the outset of Covid-19 we have taken all the necessary precautions to ensure their health and safety.
“We have followed relevant guidelines and advice from the Government and health officials and continue to do so.
“In line with Government, Transport Scotland, Health Protection Scotland and Maritime and Coastguard Agency advice, NorthLink Ferries continues to operate sailings between the Scottish mainland and the Northern Isles, but with a significant number of changes made to the on board offering.”
“This includes suspension of the cinema, car valet, closure of on-board shops and bar area, and suspension of MV Hamnavoe bed and breakfast.
“Due to the duration of crossings between Aberdeen, Kirkwall and Lerwick, food and drink will continue to be available on board, but with an amended menu.
“Stricter enforcing of social distance requirements are also in place.
The Scottish Government, which funds the NorthLink contract, said the Maritime and Coastguard Agency (MCA) issued advice yesterday “for operators to consider given the current situation” on “closing bars and reducing or amending food service provision”.
A spokesperson said: “Following updated advice from the MCA, Serco Northlink Ferries has decided to close shops and bars on board their vessels, as well as suspend services like cinemas and car valeting.
“Serco Northlink Ferries will also continue to take guidance from Transport Scotland's Resilience Team and Health Protection Scotland.”
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