Four of the 80-metre vessels are on standby to guard British waters from EU fishermen in case no deal is agreed on fishing rights after the Brexit transition period ends on 31 December.
The Ministry of Defence, confirming the move, said the deployment of the boats had been agreed as part of planning for the end of the transition period.
According to The Times, patrol powers will be beefed up with Navy officers allowed to board foreign vessels and arrest fishermen if no deal is reached.
Fishing has been one of the sticking points in talks, which are fast approaching their end on Sunday with both sides saying no deal is likely.
Access to each other’s waters will end next year, although Brussels has called for the current terms to continue for 12 months – a request that appears to have been rejected.
Tory MPs have urged Boris Johnson to ensure UK waters will be protected if talks collapse.