An announcement on Morrison's official website earlier this week said the Brown Eyed Girl and Moondance singer had become the proud father of a new son, George Ivan Morrison III.
It added that the newborn was the "the spitting image of his daddy" and was a dual citizen of the United Kingdom and the United States. The news was published around the world.
But a statement issued on the veteran singer's behalf said the report was "completely and
utterly without foundation".
Website hit by hackers
"Claims were made relating to my personal life in a 'statement' purporting to come from me. Once these claims were brought to our attention, they were taken down from the site."
Morrison is said to have asked his management to investigate "a hacking attack which took place on my website on December 29th last".
The original announcement said the child was born to Morrison and his wife and manager Gigi Lee on Monday.
But a PR executive said the reclusive musician had assured him the story was "completely false" - and that he had not heard of Gigi Lee.
"None of it is true," said John Saunders, of Fleishman-Hilliard International, adding that it was the second hacking incident to hit the website in three months.
Star 'happily married'
"When I spoke to Van a short while ago I said, like, do you even know this person and he has never heard the name at any stage in the past. He doesn't know who this person is."
Morrison's statement added: "For the avoidance of all doubt and in the interests of clarity, I am very happily married to Michelle Morrison with whom I have two wonderful children."
Van Morrison's website had a message on its front page Thursday saying only: "New website coming soon."
Van Morrison - known to his fans as Van the Man - first found fame in the 1960s with the band Them, but his solo career took off with Astral Weeks in 1968, widely regarded as a groundbreaking album.
He has continued recording regularly, and last year performed Astral Weeks live for the first time in 40 years.
