Country songstress Taylor Swift has received death threats over her alleged romance with One Direction star Harry Styles.  

X Factor US co-host Mario Lopez confirmed that things were hotting up between the pair on his radio show last week, but not everyone has taken kindly to the rumours.

Speaking on his 104.3 MY FM US radio show, Lopez says he witnessed the pop star pair getting cosy ahead of Swift's November 15 performance on the hit TV talent show.

He revealed to listeners: "Taylor Swift was the special guest performer, and [here's] a little inside scoop for you. During rehearsals, Harry from One Direction came and slapped me on the back, and said, 'Hey, Mario, how ya doing?' And I said, 'What are you doing here?' And he sort of [pointed] toward Taylor."

Lopez later added that Styles and Swift were seen "walking off hand in hand."

One Direction - also comprising of Louis Tomlinson, Zayn Malik, Niall Horan and Liam Payne - have a loyal female following, and some have taken to Twitter to vent their frustration in a string of posts aimed at Swift.

One Twitter user wrote: "Taylor Swift, when i find you, i will kill you! @Harry_Styles is MINE!!" while another Styles fan added: “I’ll murder Taylor Swift. She will not date my Harry (sic)."

One Direction fans have used the internet to target girls associated with the band before.

Xtra Factor host Caroline Flack was forced to post a public messages to their fans to stop the hatred when she was linked to Styles.

She wrote: "Hi one direction fans! To clarify. I'm close friends with harry.. He's one of the nicest people I know… I don't deserve death threats :) x (sic)."