Passengers travelling by ferry to the Channel Islands from the UK and France will need to prove they have a negative coronavirus test before boarding.
Condor Ferries is tightening safety measures following the recent increases in Covid-19 infection rates in the UK.
Passengers will need to provide evidence of a negative test result conducted within 72 hours of travel.
These changes apply to all routes, except those leaving Guernsey, and will be in place for the foreseeable future.
Secure freight supplies
In addition the Commodore Goodwill will no longer carry passengers and will operate a freight-only service from Portsmouth.
Elwyn Dop, Condor's operations director, said the decision was made to "protect those travelling" and keep freight supplies secure for islanders.
"We fully understand that the changes may be inconvenient to some but are working in the best interest of the islands as a whole and feel this is the best option available to us," he added.
The firm said customers are being notified of the changes and booking fees will be waived for those who need to change their travel.
Mr Dop said Condor Ferries was in direct dialogue with the States of Guernsey and the Government of Jersey on the topic.