There will be no passenger sailings on Condor boats until after Thursday 14 May.
The extension includes all high speed services from Poole and St Malo.
The decision was made to minimise the effects of the coronavirus outbreak and ensure food and other items are supplied to the islands.
The company stopped allowing passengers on-board on Monday 16 March.
We have to react to the changing circumstances and government-imposed constraints on travel, which have regrettably led us to cease Poole and St Malo sailings for a further two weeks. This is a very difficult and inconvenient situation for everyone, as we have now cancelled seven weeks of our busy spring schedule which are so important for the visitor economy and travel for Islanders.
All passengers affected by the cancellations will be offered a re-booking or travel voucher which is valid for 18 months.