Prime Minister David Cameron and The Prince of Wales, representing the Queen, are flying to Saudi Arabia today following the death of King Abdullah bin Abdulaziz.
They will join a host of international dignitaries in Riyadh to pay their respects to the Saudi royal family.
King Abdullah, 90, died on Thursday evening after almost two decades leading the world’s biggest oil exporter.
Both Mr Cameron and the Queen said they were “saddened” by his death.
Their decision to fly to Saudi comes amid sharp criticism over a decision to lower flags at Whitehall and across England a mark of respect for the late monarch.
Downing Street and Whitehall buildings, including Westminster Abbey and Buckingham Palace, were instructed by the Department for Culture, Media and Sport on Friday to lower the Union Flag for 12 hours in tribute.
But some politicians and human rights campaigners have slammed the tributes to Abdullah who presided over a country where a woman was recently beheaded in public, a blogger was sentenced to receive 1,000 lashes for ‘insulting Islam’ and where women have been banned from driving.
But Westminster Abbey argued refusing to lower its flag would not have helped the “desperately oppressed Christian communities of the Middle East”.
“For us not to fly at half-mast would be to make a noticeably aggressive comment on the death of the king of a country to which the UK is allied in the fight against Islamic terrorism,” a spokesman said.
A spokesman for UKIP leader Nigel Farage said lowering the flags showed “respect for an ally in the war against terror” and that the issue of human rights should be taken up with the new king.
But one of his MPs, Douglas Carswell, disagreed, saying officials had seriously blundered and showed “immoral” values far from those of the British public.
Referencing the civil service mandarin from television series Yes Minister, he said: “Sir Humphrey’s values need to be aligned more closely to people in this country rather than being quite so immoral.
Archbishop of Canterbury The Most Rev Justin Welby told Sky News: ‘Freedom of religion is essential and freedom to express Christian faith in Saudi Arabia is something that should happen.
“A few weeks ago there was a group of migrant workers arrested for holding a private service in a flat. That’s not right.
“But I know that King Abdullah himself – it’s a complicated place Saudi Arabia, like all countries – King Abdullah himself is someone who has worked very very hard on these issues and has contributed much and I think it’s right that the prime minister should send condolences and should recognise what he’s done over the years.”
King Abdullah had run the country as de facto leader since the mid-1990s after his predecessor King Fahd suffered a debilitating stroke.
He was admitted to hospital on 31 December suffering pneumonia and the royal court announced that he was breathing with the aid of a tube.
He has been succeeded by his 79-year-old half-brother, Salman.