Irish Taoiseach Enda Kenny said Margaret Thatcher was "a formidable leader" who "defined an era in British public life."
He said: "Mrs Thatcher was a formidable political leader who had a significant impact on British, European and world politics. During her 11 years as prime minister, she defined an era in British public life.
"While her period of office came at a challenging time for British-Irish relations, when the violent conflict in Northern Ireland was at its peak, Mrs Thatcher signed the Anglo-Irish Agreement which laid the foundation for improved North-South cooperation and ultimately the Good Friday Agreement.
"I extend my deepest sympathies to her family and the Prime Minister David Cameron."
More top news
Monica O'Connor and at least two other people were killed in the incident, and a British man remains missing.
Lively downpours across the south, Wales and Northern Ireland today - slow moving and intense with hail and thunder.
"The council's inspector judged there was an imminent health risk and an immediate voluntary closure of the takeaway was agreed."