The Prince of Wales has been accused by a human rights organisation of not caring enough about the "crushing of dissent" in Bahrain as details of his trip to the Gulf state were announced.
Human Rights Watch also criticised the Government, which requested Charles and Camilla tour the region, for standing "squarely and cravenly" behind the Bahrain administration, which has been accused of a string of abuses since pro-democracy protesters were violently suppressed during the Arab Spring of 2011.
Amnesty International UK called on the heir to the throne to speak out about universal values like free speech and open debate when in the Middle East.
Charles and Camilla will spend seven days touring Oman, the United Arab Emirates (UAE) and Bahrain next month - and their trip will include an ambassador's reception to commemorate the 200th anniversary of formal relations beginning between the UK and Bahrain with the signing of a Treaty of Friendship.
The campaigning organisation Human Rights Watch has described Bahrain's human rights climate as remaining ''highly problematic'' on its website.
It added: ''The country's courts convict and imprison peaceful dissenters and have failed to hold officials accountable for torture and other serious rights violations."
It is understood that the Prince and Duchess are aware of concerns organisations have raised about human rights in Bahrain.
A Human Rights Watch spokesman said: "Prince Charles has been an active advocate for the causes that are close to his heart, so he clearly doesn't care too much about the crushing of dissent and the jailing of activists in Bahrain.
"The Prince will no doubt have ardent support for this trip from the British Government who have stood squarely and cravenly behind the Bahrainis as they have dismantled civil society and locked up their critics."
Britain has a long-standing political, military and economic relationship with the Gulf state - which gained full independence in 1971 when it signed a new Treaty of Friendship with the UK.
But the British Government's relationship with Bahrain was criticised in a report by the Commons Foreign Affairs Select Committee published in April.
MPs said there was ''plainly a perception'' that the issue of human rights had been downgraded in the Government's dealings with countries like Saudi Arabia, Egypt and Bahrain.
In response to the MPs' criticism, the then foreign secretary Philip Hammond defended his department, saying: ''Improving human rights is a core function of the Foreign Office and is the responsibility of every British diplomat around the world.''
Amnesty International UK's head of policy and government affairs Allan Hogarth said: "We're not expecting Prince Charles to reinvent himself as a human rights campaigner on this trip, but we hope he'll use some of his time to speak about universal values like free speech and open debate."
He added: "In particular when Prince Charles meets King Hamad we'd like him to raise the plight of Nabeel Rajab. Mr Rajab is facing a lengthy prison sentence for his online remarks about the torture of detainees in Bahraini jails as well as the country's role in the controversial conflict in Yemen.
"Sadly, UK ministers have recently bent over backwards to paint a picture of Bahrain as a country pushing ahead with 'reforms' - the much darker truth is that it's a country hounding and locking up its dissidents."
Complete details of the royal couple's itinerary have yet to be finalised so it is not yet known if they will meet Bahrain's King Hamad bin Isa Al Khalifa, who has known the Queen and her family for many years, or senior politicians.
There is a precedent for Charles responding to concerns about human rights in foreign countries, as last year he was praised by a campaigning group when he took the decision to raise the plight of jailed Saudi blogger Raif Badawi with Saudi Arabia's King Salman.
Highlights of the tour - which begins on November 5 - include Charles visiting an Omani nature reserve, touring the Bu Tinah archipelago in the UAE, and being welcomed to the Royal Navy's base in Bahrain in his role as Admiral of the Fleet.
The royal couple will visit the Sheikh Zayed Grand Mosque in Abu Dhabi, to attend an event promoting religious tolerance, and travel to an historic UAE fort to launch the UK-UAE Year of Culture, which has Charles as its British patron.
Camilla will attend a number of events focusing on her own interests, and will tour a shelter for domestic violence, child abuse and human trafficking victims in the UAE, highlight the achievements of women entrepreneurs in Oman and visit Bahrain's Supreme Council for Women.