Die hard One Direction fans have threatened to kill Melissa Whitelaw following reports that the Australian supermodel is dating Niall Horan.

The 21-year-old law student has been bombarded with vile messages from obsessed Directioners on social media after was seen kissing the singer in a casino in Melbourne.

Furious fans flocked online to warn the brunette beauty to stay away from the Steal My Girl hitmaker, with one even threatening to " f**k her up".

Although Horan has not responded to the online abuse, an account believed to belong to Whitelaw took to Instagram pleading for the harassment to stop.

"I haven't done anything to any of you so please stop sending me mean comments," she said.

The handle @edgeofmydesire later added: "For all you asking yeah Niall and I dating. Niall has not posted about because we have decided we will wait until it's the right time."

One unimpressed fan replied: "Someone said to me Melissa and niall look cute together. Let's just say I will not be showing at her funeral and I did not kill her."

The couple sent the rumour mill into overdrive earlier this month when a girl resembling Whitelaw was seen leaving a flight right behind the Irish heartthrob in Sydney during One Direction's On The Road Again Tour.

In January, Horan made headlines when his bandmate Harry Styles appeared to ask him for oral sex on social media.

After Horan shared a selfie with his tongue out on Instagram, Styles responded with a proposition. "Can I sit on your face?" he wrote in the comment section before adding "Please?".