One Direction star Niall Horan's rumoured girlfriend has urged the band's devotees to stop sending her vile notes on social media, threatening to harm her if she breaks the pop star's heart.

Melissa Whitelaw's Instagram page has been bombarded with comments from Horan's fans, with some insisting she doesn't deserve to be his girlfriend, while one obsessed devotee warns, "I swear if you (do) something bad to niall we will kill you. I am not even kidding."

Another twisted fan writes, "I don't like you. You aren't nialls gf (girlfriend). Niall is way better than you and don't deserve you. He can do better. You just like broke up with your ex bf (boyfriend) and niall knows that and wouldn't kiss you."

In fact Horan was spotted kissing Whitelaw at a casino during a day off from touring in Australia.

And now the pretty 21 year old student and blogger has responded to the abuse on social media, stating, "I haven't done anything to any of you so please stop sending me mean comments."