The UK has brought forward plans to send a second warship to the Gulf amid rising tensions with Iran.
HMS Duncan is currently in the Mediterranean and is expected to join HMS Montrose in the region next week.
It comes after the UK government said Iranian boats tried to impede a British oil tanker in the Gulf on Wednesday.
Meanwhile, Iran has reiterated calls for the UK to release an Iranian-owned oil tanker that was detained by Royal Marines in Gibraltar last week.
An Iranian official, speaking to state news agency IRNA, warned the UK not to get involved in “this dangerous game”.
The relationship between the UK and Iran has become increasingly strained in recent weeks.
On Tuesday, the UK raised the threat to British shipping in Iranian waters in the Gulf to the highest level – where the risk of attack is critical.
The following day, boats believed to belong to Iran’s Islamic Revolution Guard Corps (IRGC) approached the British Heritage tanker and tried to bring it to a halt as it was moving out of the Gulf into the Strait of Hormuz.
HMS Montrose, a British frigate shadowing the BP-owned tanker, was forced to move between the three boats and the ship, a Ministry of Defence spokesman said.
Iran denied any attempted seizure.