The Tanaiste’s comments came after Fine Gael candidate for the Irish presidency suggested a Stormont parliament could be retained in a united Ireland.

Rival presidential candidate Catherine Connolly accused the Government of not doing enough to plan for constitutional change on the island

Mary Lou McDonald said there was space for humour in the conversation around Irish unification.

The former taoiseach outlined a series of proposals on the constitutional question at an event in Derry on Thursday.

A report examines the current economic relationship between both sides of the border, and the potential of an all-island economy.