Calvin Harris

The track is called Better Man but she won't be singing it herself - it's been penned for country band Little Big Town.

"But your jealousy, I can hear it now," go the lyrics, "you're talking down to me like I'll always be around".

"You push my love away like it's some kind of loaded gun" she also writes.

The band has confirmed in a Facebook Live Q&A that Taylor is behind the track.

"She sent us this song, and it was one that was really special to her," singer Karen Fairchild explained to fans.

The prolific DJ/producer talked to British GQ about his 15 month relationship and subsequent split with the pop star.

Harris told the publication "It's very difficult when something I consider so personal plays out very publicly."

Rumours had been circulating online that she was the lyricist behind This Is What You Came For, which features Rihanna.

Swift's representative confirmed it to People magazine, which the DJ retweeted from his official account.

He wrote: "Amazing lyric writer and she smashed it as usual."

The DJ and producer tweeted, "The only truth here is that a relationship came to an end & what remains is a huge amount of love and respect" after news broke recently that he and Swift were done.

Swift, who was with Harris for 15 months, retweeted him.

There has been much speculation about what happened with the pop power couple.

In the May issue of Vogue, Swift talked about her relationship with Harris, whose given name is Adam Wiles.

It's understood the American popstar was still in Queenstown this morning and left on a private jet about 8.30am.

She has now landed in pouring rain in Australia. The plane taxied inside a hangar so she didn't get wet.

The 25-year-old landed in New Zealand on Monday, skipping the American Music Awards and sparking a furore among fans eager to catch a glimpse of her.

But there weren't many to be had, with only a grainy photo of her on Bethells Beach taken. At times she was rumoured to be in East Tamaki, Henderson and at Lorde's parents' bach south of Auckland.