The 890-year-old heart of St Laurence O'Toole was stolen in March by two men who prised open a protective cage.
According to the Dublin Sunday Independent, detectives have established a link with the illicit theft and sale of rhino horns, which are sold in powdered form as a traditional medicine in China.
The report said gardai were trying to establish whether an Irish gang had found another niche market in stolen items, and were in contact with other European police forces.
The dean of Christ Church, the Very Rev Dermot Dunne, said on Saturday that the loss of the St Laurence relic "felt like part of the fabric of the cathedral has gone". He said there was a market for "class one" relics, which are reputedly the remains of saints, mainly in the Americas and Asia.
Irish gangs have in the past been involved in the theft of antiques and art, initially targeting big country houses. In the 1980s and 90s many Irish houses were stripped of antiques, which were shipped first to the UK and then to the continent to be sold at fairs.
