"The EU can not be held hostage on a long-term basis to the resolution of a political crisis in the United Kingdom", he said.
McAleese, who was speaking during the Dublin City University (DCU) Brexit Institute Conference on the UK's withdrawal from the European Union, said there is a need to ensure the "groundwork is laid" ahead of any Irish unity referendum.
"I'd like to say here that we will never abandon Ireland or the Irish whatever happens because that solidarity is the whole meaning of the European project", he added.
Varadkar stressed there was still time for the British prime minister to come to the European council before 10 April with "credible" proposals, and he said the EU should be open to such proposals.
Speaking to RTE News in Cork, Mr Coveney said: "In the absence of a British Government co-operating in the way that they have committed to, to actually prevent checks on the island of Ireland, well then we need to try to come up with another plan".
The UK parliament has three times rejected her divorce deal with the EU.
"We have instead now this opportunity to develop a wholly fresh focus on the future, making it a place of transcendence, where multiple identities can be respected, be accommodated, can grow to become one community, gathered around the principles of the Good Friday Agreement and the European Union".
The Irish premier met with Macron ahead of talks with Germany's Chancellor Angela Merkel in Dublin.
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She earlier posted photos while she was undergoing hair changes and the same confirmed that her new look was permanent and not a wig.
He said he will use the meetings to discuss the "possible scenarios arising from this week" - including ongoing efforts to secure ratification of the Withdrawal Agreement and the European response to any potential United Kingdom request for a longer extension.
"We are preparing for all outcomes, and have prepared intensively for a No Deal".
"Long before any future referendum goes live, we need to do what Brexit has abjectly failed to do".
Speaking after the indicative votes, Mr Dodds said the only proposition that MPs had ever supported was an amendment - known as the Brady amendment - calling on the government to negotiate changes to the backstop.
Speaking alongside Mr Macron, he said: "The UK is very much consumed by Brexit but Ireland, France and the European Union shouldn't be consumed by Brexit".
"As things stand, the United Kingdom will leave the European Union on 12 April without a deal".