Speaking out, Kian - who found fame in the Irish group in the 90s - apparently said he felt 1D did not have the "tight bond" needed to last in the industry.
"One Direction would be fools to throw it away, absolutely fools - and I get the feeling they will," he told An Irishman Abroad.
"I watch them and they don't seem to have this bond as tight as we had in Westlife - especially as they've only been together three or four years."
Kian was also heard saying that the music industry in the 90s was a very different ballgame, as bands had to shift physical copies of singles and albums, making it harder to achieve a No 1.
"I say this in no disrespect to One Direction, but One Direction will never sell what Westlife sold," he said.
Unfortunately, the comments have now riled some 1D fans. One blasted on Twitter: "Kian Egan's trying to drag 1D so hard I don't understand why."
Another added: "@KianEganWL I'm afraid @onedirection passed you out in popularity about 4 years ago x."
Responding to the critics, Kian has now taken to Twitter and said: "One Direction Fans. This is totally taken out of context once again. Papers looking to make something out of nothing."
After reading his message, a Kian fan replied: "Westlife will always be the best boyband ever! cz you guys have a true friendship! We love you!!!"
Now now everyone, just calm down!
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