The Duchess of Cambridge's family tree on her dad Michael Middleton's side can apparently be traced back to former King of England Edward III and de Burgh is an ancestor of 14th century Irish heiress Elizabeth de Burgh, who married Edward III's son, Lionel of Antwerp.
At a genealogy roadshow for the BBC's Who Do You Think You Are? programme, last week, Niall Gibbons, the chief executive of Tourism Ireland, said Kate's links to Ireland had also been authenticated, 'The Sunday Times' reported.
Although Tourism Ireland is yet to release its findings, it is understood they claim that de Burgh's mother was Maeve Emily de Burgh, daughter of General Sir Eric de Burgh, a British army officer who became chief of the general staff in India.
The British-Irish pop singer, who was born in Argentina and has sold 45m records worldwide, said the link was a surprise, the report said.
"I was unaware that there is a distant connection between the de Burgh family and the Middletons," said de Burgh.