Thousands of fans were duped into visiting a page on Facebook.com which was set up in the Irish pop star's name and encouraged devotees to 'like' the page to raise money for sick kids.
A message posed on the page claimed a $100,000 (£62,500) donation would be made to a children's hospital if it reached "100,000 likes".
However, a representative for One Direction is adamant the page is fake and has promised to contact Facebook.com bosses to get it taken down.
The rep says, "Yes, I'm afraid this is not Niall unfortunately. We will have Facebook shut this down."