Ireland's Taoiseach Simon Harris had a blunt response to former British Prime Minister Boris Johnson's claim that US President Joe Biden told him he's "not  really Irish."

Johnson, who was Prime Minister from July 2019 through September 2022, wrote of his and Biden's engagements surrounding Brexit in his newly released memoir "Unleashed."

According to The Irish Times, Johnson wrote in his memoir: “In fact, he [Biden] disarmed me completely by saying that his family origins were not really Irish at all, and that the Bidens were an old seafaring family from Kent (which seems plausible, since -den is a common Kentish termination).

“I suppose he may say something else when in Dublin. But never mind!”

On Friday, Harris was asked about the unexpected claim while on Newstalk's Pat Kenny Show.

Tongue in cheek, Kenny asked Harris: “You’re heading to the White House next week. We need vital clarification when you’re on your mission to the White House and that is the question  you must ask Joe Biden which is, ‘Are you Irish or are you not?”

Laughing, Harris replied: “There are very many pressing and serious issues that of course I want to speak to the President of the United States with, including our diplomatic relations, but --”

Kenny interjected: “What do you think Boris Johnson is up to? Is he being mischievous?”

Harris swiped: “I think one question I definitely don’t need clarity for is if Joe Biden considers himself Irish.

“I think Boris Johnson is a person who seems to be very good at selling books and I hope he’s certainly much better at that than he was at being a politician.”

Biden does have a British link - his great-great-great grandfather William Biden was from Westbourne in West Sussex, England, and later emigrated to Maryland in the US.

However, his Irish roots are more apparent - all eight of his great-great-grandparents on his mother's side were born in Ireland, as were two of his great-great-grandparents on his father's side, making it not surprising that the US President loudly embraces his Irish heritage.

The Department of the Taoiseach announced on September 24 that Harris accepted an invitation to meet Biden at the White House in October.

Ahead of his US visit, Harris - who received a phone call from Biden in June after becoming Taoiseach - indicated he won't "shy away from" potentially difficult topics - especially concerning the Middle East - with the outgoing US President.

“I’m proud of the diplomatic relations between Ireland and the United States of America, and I believe the overwhelming majority of people in this country are too," Harris told reporters in Dublin on Wednesday, according to the PA.

“I’m also proud of the tradition of taoisigh and presidents being able to engage on issues too.

“But you also speak the truth to your friends. And Ireland’s never afraid to speak our view. And I’m not afraid of that either. We speak the truth. We speak up for our foreign policy.

“We have an independent foreign policy, and our independent foreign policy is very clear in relation to what should happen in the Middle East.”

Not long after becoming Taoiseach earlier this year, Harris announced in May that Ireland, in concert with Norway and Spain, would be formally recognizing Palestine as a state. Including Ireland, Norway, and Spain, 145 out of the 193 UN member states have now recognized a Palestinian state. The US is not among them.

An alternative Biden Harris! A great honour to meet President Biden in Ireland. Thank you Mr President for your friendship. Enjoy your visit to @MayoRoscHospice today - something you supported so much, that was important to you & through that work we remember your son, Beau pic.twitter.com/yFkqshkRCp

— Simon Harris TD (@SimonHarrisTD) April 14, 2023

Harris said on Wednesday that he has “absolutely no doubt” that the Biden administration, "led through the efforts of Secretary of State Antony Blinken," has been trying to bring about a ceasefire.

"I’ve no doubt the EU wants to see a ceasefire," Harris, who along with other Irish leaders has repeatedly called for a ceasefire, added.

"I can say all of that, though, and also say the next sentence – all of the efforts have been utterly ineffective to date, because we still don’t have a ceasefire.

“So all of us – big countries, small countries, Europe, the United States – need to now say ‘what more can we do to bring the world back from the brink?’

“Because this is an extraordinarily dangerous moment. So, of course, we continue to engage with the United States.

“Of course, we’re proud of the diplomatic links between the United States and Ireland, but we can also have, and do have, our own independent foreign policy, which we articulate at every possible opportunity.”