He was speaking after An Taoiseach Leo Varadkar told the BBC that he wouldn’t like to see constitutional change ‘on a 50% plus one basis’.
Raymond McCartney commented: “The Good Friday Agreement is absolutely clear in enshrining the right of the Irish people to self-determination through referenda, north and south.
“If a simple majority vote in favour of reunification, both governments are then obliged to legislate for it.
“The Good Friday Agreement is the legal and internationally-biding position.
“There is an onus on the Irish government to plan for unity. To become a persuader for unity. To build the maximum agreement and to secure and win a referendum on unity.
“As a co-guarantor of the Good Friday Agreement, the Taoiseach should be seeking to defend the agreement in all its parts, not seeking to undermine it.,” added the Foyle MLA.