Two senior PSNI officers were deployed as "critical friends" of the Sri Lankan regime around the time of a civilian massacre by government forces in 2009.
Documents reveal how the UK worked with Sri Lankan security forces during the final stages of the bloody civil war which devastated the country.
British police secretly advised the Sri Lankans since the Thatcher era, with visits to the Royal Ulster Constabulary's headquarters during the Troubles and early guidance from an ex-MI5 director on counter-insurgency strategy.
It was previously revealed how 3,500 Sri Lankan police officers – including some senior commanders – received training from the Scottish Police College since 2007.
It has now emerged UK police training in Sri Lanka continued even during the bloodiest months of the war.
The links to Northern Ireland were revealed following a Freedom of Information request to the PSNI by Corporate Watch, a not-for-profit research group.