A Bahraini prince at the centre of long-running allegations of torture is leading his country's racing delegation at Saturday's Royal Windsor Horse Show, attended by Britain's queen.

Nasser bin Hamad al-Khalifa has faced and denied repeated allegations in the UK from a Bahraini refugee over the torture of pro-democracy activists in the country's 2011 uprising.

An Arabic article on the al-Wasat news website states that the prince, who is the son of King Hamad bin Issa al-Khalifa, is leading a team of eight horses at the event on Friday.

Buckingham Palace would not say who the queen would meet at Windsor, stating to Middle East Eye that she was attending in a "private capacity".

However, the prince's presence in the UK was condemned by the UK-based Bahrain Institute for Rights and Democracy (BIRD), which said the UK was hosting an "alleged torturer" while pro-democracy campaigners languish in Bahraini jails.

A protest was being organised against Bahrain's presence at the event, said the Campaign Against Arms Trade.

The prince's visit also comes days after the Bahrain government stated it had implemented all 26 recommendations of the Bahrain Independent Inquiry Report, which found systematic use of torture after the 2011 uprising.

The US State Department said on 12 May that the statement was questionable, and concerns remained over "limitations on peaceful assembly and political activism, the criminalisation of free expression, and the importance of reconciliation".

The UK's embassy said on Twitter: "HM Amb Martin welcomes Prof Bassiouni's assessment of BICI implementation, reaffirms #UK commitment to further reform assistance to #Bahrain".

HM Amb Martin welcomes Prof Bassiouni's assessment of BICI implementation, reaffirms #UK commitment to further reform assistance to #Bahrain — UKinBahrain (@UKinBahrain) May 11, 2016

Allegations against Prince Nasser, from the refugee known as "FF", have been before British courts on several occasions. The prince lost diplomatic immunity in 2014 after the High Court in London overturned a previous ruling by the Crown Prosecution Service.

FF's linked the prince to widespread torture during the uprising of 2011, but did not say he was directly responsible.

The prince has said he "categorically denies" the "politically motivated" claims, London's Metropolitan Police says there is no evidence against him, and the British government said Nasser was “welcome” in the UK.

Prince Nasser has visited Britain at least once since the high court ruling, in late 2015, during which he met defence officials and the prime minister's Middle East envoy.

During that visit campaigners presented what they said was a new "dossier" to Scotland Yard. No charges were brought and the prince said in a statement the timing of the "dossier" showed it was politically motivated.

Less than a month later, the UK struck a deal to establish a new Royal Navy base in Bahrain.

Sayed Ahmed Alwadaei, BIRD's director of advocacy, said: "The UK is destroying its credibility on Bahrain when it stands shoulder-to-shoulder with Bahrain's repressive monarchy, celebrating the false end of reforms and hosting an alleged torturer at Royal Windsor, while rights defenders and democracy advocates continue to serve unjust prison terms."

BIRD raised the plight of Zainab al-Khawaja, who remains in prison on charges of insulting the king despite reassurances over a month ago that she would be released.

Royal Windsor hosts alleged torturer Prince Nasser today, while in Bahrain Issa Prison hosts Zainab al-Khawaja + son pic.twitter.com/HqnEG1Epcc — Nicholas McGeehan (@NcGeehan) May 13, 2016

The State Department has called for her release several times, most recently on 12 May.

The UK has "raised Zainab al-Khawaja's case" with the Bahraini government, but has never called for her release, BIRD said.

Andrew Smith, of the Campaign Against Arms Trade, told Middle East Eye: "Unfortunately this is just the latest example of the hypocrisy at the heart of UK foreign policy.

"There are serious torture allegations against Nasser and rather than call for him to be investigated the UK government is greeting him with open arms."

"No matter how bad the human rights situation in Bahrain gets, the regime is always able to rely on the uncritical political and military support of the UK government. "

The Wasat article said the prince would be at Windsor to promote Bahrain's ambitions to become world leaders in horse eventing. He is due to race on Saturday.

A spokesman for Buckingham Palace told Middle East Eye: "The queen attends the RWHS in a private capacity so we are not able to say who her majesty might meet in the coming days."