Katy Perry has fallen victim to an Internet hacker, who took over her Twitter page and leaked an unreleased song.

The Roar hitmaker's account was taken over on Monday (30May16), when a message going out to her 89 million followers read, "haha follow @sw4ylol #hackersgonnahack."

The user "@sw4ylol" is reportedly based in Romania and only started the account a few days ago, but after the message was sent from Katy's page, the anonymous user sent a tweet on their own account which read, "Who TF (the f**k) is Katy Perry."

However, @sw4ylol clearly knows who the pop star is, after leaking an unreleased track by Katy called Witness 1.3 via a SoundCloud link.

Back on Katy's page, the hacker sent off a series of vulgar and nonsensical tweets, including, "otf gang n**ga!", and "u a f** @keemstar," mentioning a blogger with more than 80,000 followers on the microblogging site.

The user also wrote, "miss u baby @taylorswift13," which seemed to be an attempt to reignite a reported rivalry between the two entertainers.

Katy and Taylor famously fell out in September, 2014, after the Style singer revealed her song Bad Blood was inspired by her feud with another female artist.

"For years, I was never sure if we were friends or not," she told Rolling Stone magazine at the time. "She would come up to me at awards shows and say something and walk away, and I would think, 'Are we friends, or did she just give me the harshest insult of my life?'"

Rumors quickly emerged she was talking about Katy.

Taylor didn't respond to the fake tweet, which was deleted with the other hacked posts minutes after they were published.

Katy's last real tweet came about five hours prior to the takeover, when she re-posted a message from presidential candidate Hillary Clinton, who remembered fallen veterans on Memorial Day.

Hillary wrote, "Our fallen heroes deserve our profound gratitude for giving their lives to protect our freedom, today and every day. #MemorialDay." Katy added, "Yes! Thank you to the heroes we’ve lost and still serving! We appreciate you and honor you today!"