HMS Westminster left Portsmouth today on a routine visit to Gibraltar amid the tensions with Spain over border checks.
The Type 23 frigate will visit the Rock en route to the Mediterranean where she will join other naval ships on a large training exercise.
She will be joined by two Royal Fleet Auxiliary ships – RFA Lyme Bay and RFA Mounts Bay.
The warship set sail at 10am.
The visit comes as a diplomatic row continues between the UK and Spain.
It was triggered by the creation of an artificial reef by the Gibraltarian authorities, which the Spanish claim will destroy fishing in the area.
Madrid responded by beefing up border controls, leading to lengthy queues, and suggesting that a £43 fee could be imposed on every vehicle entering or leaving the territory through its fenced border with Spain.
Reports in the Spanish media suggest the row could escalate to the United Nations, with Mariano Rajoy’s government receiving support from Argentina.
Spanish foreign minister Jose Garcia-Margallo is expected to propose that both countries present a united front over Gibraltar and the Falkland Islands, El Pais reported.
A Foreign Office spokeswoman said: ‘Our policy on Gibraltar has not changed and is consistent with our policy on other overseas territories.
‘Self-determination matters more than territorial integrity.
‘The people of Gibraltar have repeatedly and overwhelmingly expressed their wish to remain under British sovereignty.’