HMS Montrose is already permanently deployed to the Gulf region (Picture: MOD).
Britain is to join a new US-led maritime security mission to protect international shipping in the Gulf, the Ministry of Defence (MOD) has said.
The MOD said the Royal Navy will work with the United States Navy in accompanying merchant shipping through the Strait of Hormuz.
The move follows the seizure last month by Iranian Republican Guards of the British-flagged tanker Stena Impero.
The MOD said the mission would "largely draw on assets" already in the region including the warships HMS Duncan and HMS Montrose.
The two warships have so far escorted 47 British-flagged merchant ships through the Strait of Hormuz.
The UK has also offered to lead one of the mission's Maritime Task Groups.
Defence Secretary Ben Wallace said: "The UK is determined to ensure her shipping is protected from unlawful threats and for that reason we have joined the new maritime security mission in the Gulf.
"The deployment of the Royal Navy assets is a sign of our commitment to our UK-flagged vessels and we look forward to working alongside the US and others to find an international solution to the problems in the Strait of Hormuz."
The Strait of Hormuz is the busiest narrow shipping passage in the world and a vital transit zone with 20% of the world’s oil passing through it every year.
At the end of July, the MOD announced the Royal Navy would be escorting British ships through the Strait amid "heightened threat to commercial shipping in the Gulf".
The UK is also set to send two more ships to the region later this year.
Foreign Secretary Dominic Raab said the deployment will "uphold freedom of navigation in the region", adding the UK remains committed to working with Iran to "de-escalate the situation and maintain the nuclear deal".
Last month, the US announced plans to create an international task force to safeguard the Gulf's waters.