The PSNI has strongly denied allegations that they provided public order training to officers from the Gulf state of Bahrain.
PSNI Assistant Chief Constable Alan Todd has admitted that police facilitated a delegation of Bahraini officers on a study visit to Belfast during the marching season in 2015.
But he insisted that the PSNI "have never provided training to Bahrain police officers in Bahrain or Northern Ireland".
Human rights group Reprieve has criticised the PSNI for "sharing its expertise on gathering intelligence ahead of parades" with around half a dozen Bahraini police officers during the visit to Belfast in August 2015.
The visit was funded by the British Foreign Office.
Reprieve said that protesters in Bahrain, which has been heavily criticised for human rights abuses, have been targeted by police and tortured into falsely confessing to capital crimes.
The human rights organisation said the Bahraini delegation to Belfast followed the PSNI's Crimson Commander at the Royal Black Preceptory parade and the Henry Joy McCracken parade in Belfast.
The visit also included sessions on water cannons, dog handling and public order tactics.
It has been claimed that the training was prepared by PSNI officers during a week-long "scoping visit" to Bahrain between April and May 2015, where they assessed Bahrain's public order systems.
"The PSNI have never provided training to Bahrain police officers in Bahrain or Northern Ireland," insisted Mr Todd.
The Assistant Chief Constable said that the British Foreign Office, through Northern Ireland Co-operation Overseas (NI-CO), made a request to the PSNI to facilitate a delegation of Bahraini officers on a study visit "to observe globally recognised best practice in human rights based public order policing".
He added: "The Bahrain delegation visited in August 2015 and, while in Northern Ireland, they observed a number of public order events and received a number of presentations on aspects of PSNI public order policing planning and delivery.
"At no time did the PSNI undertake any form of training with the officers. As an organisation recognised across the world for placing human rights at the centre of policing, the PSNI are often asked to host study visits from international policing bodies.
"This is viewed as part of our responsibility to participate in the development of global policing standards."
However, Reprieve director Maya Foa criticised the PSNI and the British Foreign Office for their involvement with Bahraini police.
She said: "Bahrain is notorious for arresting, torturing and sentencing to death people involved in protests, such as Mohammed Ramadan, a father of three who is held on death row and faces execution at any moment.
"By training Bahrain's police how to gather intelligence on protesters, there is a serious risk that Britain is helping them arrest and execute people who are guilty of nothing more than calling for reform.
"It is scandalous that the (British) government has sought to sweep this under the carpet."