The UK and Iran have summoned each other's diplomats in a row over last week's attack on an Israeli ship oil off the coast of Oman resulted in the death of two crew members- a Briton and a Romanian.
The UK, US and Israel blame Iran for the deadly attack. Tehran dismissed the accusations.
The move increased tensions in the region as US Secretary of State Anthony Blinken said he was consulting with the UK, Israel and Romania and there would be a "collective response".
On Monday, the UK summoned Iran's ambassador over what the British government called the "unlawful attack".
British Prime Minister Boris Johnson said Iran should "face up to the consequences of what they've done" calling the incident an "an unacceptable and outrageous attack on commercial shipping".
Iran summoned the British Chargé d'Affaires in Tehran as well as Romania's top envoy to express objection against the accusations.
