The new advice, published on Monday (13 July), stops short of advising against travel to the Middle East, but warns that hostilities could resume at short notice after the US and Iran's ceasefire lapsed last week.
British nationals in the United Arab Emirates, Qatar, Saudi Arabia and Oman are advised to follow any guidance from local authorities, monitor local and international media, keep departure plans under review, and be prepared to shelter indoors if instructed.
The updates also warn that, prior to the ceasefire, Iran had stated its intention to target locations in the Gulf associated with the US and Israel, including civilian infrastructure such as ports, airports, hotels, roads, bridges, energy facilities and water systems.
The changes come days after the FCDO strengthened its advice for Bahrain and Kuwait, adding similar warnings that Iran has carried out further attacks since agreeing a memorandum of understanding with the US and could "do so again at short notice".
The latest updates follow a sharp deterioration in the regional security situation. The US carried out a third consecutive night of strikes against Iran on Monday, while two tankers have reportedly came under fire in the Strait of Hormuz.
US President Donald Trump also announced plans to reinstate a blockade of Iranian shipping in the Gulf, alongside a proposed 20% security fee for vessels transiting the Strait of Hormuz, saying the waterway would remain open "with or without Iran". Tehran rejected the move, insisting it would remain the guardian of the strategically important shipping route.
The renewed tensions raise fresh uncertainty for the travel industry after confidence had begun to recover following the easing of FCDO advice in June.
On 18 June, the FCDO relaxed its guidance for the UAE, Qatar, Oman, Saudi Arabia and Bahrain after a ceasefire between the US and Iran, prompting an immediate rebound in bookings and enquiries.
Travel agents reported renewed demand for Gulf holidays and greater confidence among passengers transiting through major hubs such as Dubai and Doha en route to Asia, Australasia and the Indian Ocean.
New consumer spending data, published by Barclays on Tuesday (14 July), also suggests travel demand had been recovering before the latest escalation.
Spending with travel agents increased by 1.9% year-on-year in June, while overall travel spending was broadly flat at -0.1% year-on-year, marking an improvement after declines of 3.3% in March, 5.7% in April and 5.8% in May when conflict in the Middle East weighed heavy on consumer confidence.
