The Taoiseach has reiterated his concerns that events in London with the Conservative Party leadership contest had increased the risk of a no-deal Brexit.
Mr Varadkar also said the result of the European election in Northern Ireland has been heard in Brussels and must be heard in London.
Speaking in Brussels, Mr Varadkar highlighted that those two candidates - Sinn Fein's Martina Anderson and the cross-community Alliance Party's Naomi Long - also supported the Withdrawal Agreement's Irish border backstop.
The DUP's Diane Dodds, a Brexiteer and critic of the backstop, was the other candidate elected.
The Taoiseach made the comments as attended a European Council meeting of EU leaders in Brussels on Tuesday.
"What I think is really significant, and I hope this has been noticed in Britain, is the result of the European elections in Northern Ireland, where for 40 years there have been two unionists and one nationalist," Mr Varadkar said.
"That is no longer the case. There is one unionist, one Alliance Party MEP and one nationalist.
"So, two out of the three of the MEPs elected in Northern Ireland supporting the European Union and supporting the backstop and I hope that hasn't been missed as a fact by the British government and the wider British people."
Mr Varadkar reiterated his concerns that events in London with the Conservative Party leadership contest had increased the risk of a no-deal Brexit
"I think there is a growing risk of no deal," he said.
"I can say is the European Union and Ireland will stand firm in our position that there can't be a hard border between Northern Ireland and Ireland and we need a legal treaty guarantee of that."