P&O Cruises and Cunard Line extended the suspension of sailings until the end of July.
The cruise companies had previously cancelled all voyages up to May 15.
Clients with affected bookings automatically receive credit for a future cruise worth 125% of the cost of the original trip.
The extension means the launch of the newest ship to be operated by P&O, Iona, will be delayed.
Sailings for Cunard Line's Queen Elizabeth were cancelled up to September 8 as the liner would not have been viable to operate a shorter summer season, the company said.
Cunard's Queen Victoria was due to visit Liverpool UK on June 16, but this won't be going ahead.
TUI Cruises have also been forced to cancel some of their sailings, with all Marella voyages cancelled until May 31.
TUI river cruises have been cancelled until November 25, 2020.
For Coronavirus updates on cruise ship quarantines (infected passengers and crew) and top-pandemic countries (COVID-19 cases and deaths, daily updated statistics) see at CruiseMapper's Norovirus page.