Boris Johnson and Prince Charles have rushed to Oman to meet the country's new ruler, following the death of its sultan.
Oman is a key strategic partner of the UK and other western countries and the death of Sultan Qaboos bin Said al Said, one of the Middle East's longest serving heads of state, comes at time of heightened tensions in the region.
Charles, the prime minister, defence secretary Ben Wallace and the UK's chief of defence staff attended a condolence ceremony after arriving in the capital Muscat.
Other heads of state and senior royals from countries including Qatar, Kuwait, Bahrain and the United Arab Emirates also paid their respects.
The Prince of Wales then travelled back to the UK in time for crisis talks at Sandringham with senior royals on Monday in a bid to find a solution to Meghan and Harry's future roles.
On Saturday, Mr Johnson released a statement expressing his sadness at the death of Sultan Qaboos, who had ruled Oman since 1970.
The prime minister met the new sultan - Haitham bin Tariq al Said - and other senior members of the Omani government.
Sultan Haitham has pledged to follow the non-interference policy that made the kingdom a vital regional mediator under his late cousin.
The Queen also released a statement late on Saturday, describing Sultan Qaboos as a "good friend".
The monarch and the sultan watched an equestrian event together in Oman in 2010 during a state visit to the country, and they both attended a banquet in Claridge's Hotel held in his honour in 1982.
In 1979, the sultan attended a dinner on board the royal yacht Britannia.
Qaboos had travelled to the UK in 1958 to attend Sandhurst and joined the British Army where he was posted to the 1st Battalion The Cameronians (Scottish Rifles) and served in Germany for a year.
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He had also studied local government in Suffolk at the age of 18 - briefly holding a post with Suffolk County Council - but returned to his country and seized the throne from his father in a bloodless coup in 1970.
Charles visited Sultan Qaboos at his palace at Bayt al Baraka on a tour of the Middle East with Camilla on March 2013 and with his then-wife Diana in 1986.
Just last month, the Duke of Cambridge held an audience with the sultan at the Palace of Bait al Baraka at the end of a four-day tour of Kuwait and Oman.
William said on Saturday he was "truly honoured" to have met the sultan and that "it was clear from all those I met that he will be remembered with great affection".
He added: "His majesty was unwavering in his commitment to improve the lives of his people, and in his resolve to work towards regional stability. I am thankful for his majesty's many years of friendship with my family and the UK."
William also met the new sultan, who at the time was his country's heritage and culture minister.
Sultan Haitham, 65, also has strong ties with the UK, having given his support to the University of Oxford's Islamic Studies centre over several years, and having graduated from the university's Foreign Service Programme in 1979, according to Arab News.
He was among those who welcomed Charles and Camilla to the country in 2013 and 2016, and William last December.