Sean Sherlock, a Labour TD for the Cork East constituency, believes that the 16th-century Mount Keefe Chalice should be returned to Ireland from England.
The Mount Keefe Chalice, which dates back to the 1590s, is currently housed at the Victoria & Albert Museum in London.
TD Sherlock said the Mount Keefe Chalice is of "significant importance to Irish culture and Irish history."
Sherlock said he has written to Tanaiste Micheál Martin, explaining that he believes "a process should be devised on a bilateral basis between the Irish government and the UK government to repatriate those items that are of Irish origin and are important Irish folklore and from a cultural point of view."
Objects of our past deepen community pride and interest in heritage.
The Mount Keefe Chalice is symbolic of many other antiquities and items of Irish origin which are housed in British Institutions.January 29, 2023
Sherlock separately told Newstalk's Lunchtime Live radio show that is a mystery how the artifact ended up in the English museum.
"By the crux of history, it ended up in the Victoria & Albert Museum in essence," Sherlock told Newstalk.
The Labour TD added that the museum appears to contain several objects from Britain's colonial past but said the chalice seems to have been sold to the museum and that "there are documents to that end".
"It did prompt me to think about the wider question of antiquities and artifacts that are Irish in nature - such as the Annals of Inisfallen, whereby that has ended up, for instance, in the Bodleian Library in Oxford," Sherlock told Newstalk.
"How did these artifacts come to arrive at very old, established British institutions?"
Sherlock said it is time for a conversation about the decolonization of Irish artifacts residing in British museums and said he has asked the Department of Foreign Affairs to look into the issue.
He added that the chalice and the story of how it ended up in the Victoria & Albert Museum should also be investigated.
"It was thought that the chalice was buried in a place near Newmarket - that's the story as I understand it.
"If the church was the benefactor of the chalice - which you would assume that it was - how did it end up coming into the ownership of somebody else... and how then did it end up in the Victoria & Albert Museum?"
Sherlock said a process of bilateral engagement would make it possible for a discussion to begin about returning colonial artifacts to their originators.
The Mount Keefe Chalice is inscribed with a Latin sentence, which translates to "COK had me made in the Year of the Lord 1590.
It also gives precedence to the shamrock leaf, which is unusual for artifacts from the period because the shamrock was not seen as a national emblem at the time. Instead, it was seen as an ancient religious symbol associated with St. Patrick.