Taylor Swift appears to have sold one of her two private jets, while her lawyers have threatened legal action against a student tracking her movements.

The singer's Dassault Falcon 900 jet had been listed under SATA LLC, a company with the same address as Taylor Swift Productions in Nashville, until 30 January, according to Business Insider.

Federal Aviation Administration data shows the jet, which had been listed under Swift's holding company since 2009, is now registered to Triangle Real Estate LLC, a company based in Missouri.

Swift still has a Dassault 7X jet, which many fans and media outlets have predicted she will use to fly from Japan to Las Vegas next week to get from her gig in Tokyo to the Super Bowl, which her boyfriend Travis Kelce is playing in.

| A Dassault Falcon 900. File pic: AP

The jet was sold a week before Swift's lawyers sent a cease and desist letter to Jack Sweeney, the creator of social media accounts that log the takeoffs and landings of planes and helicopters owned by billionaires, politicians, and other public figures.

The lawyers described the University of Central Florida student's actions as "reckless" and said the singer lives her life "in a constant state of fear for her personal safety".

"While this may be a game for you or an avenue that you hope will earn you wealth or fame, it is a life-or-death matter," the 14-time Grammy winner's lawyers wrote in the letter, provided by Mr Sweeney to NBC News - the US partner of Sky News.

Swift's lawyers accused Mr Sweeney of "stalking and harassing behaviour" in the letter - an allegation the student's own lawyers have firmly rejected.

According to Mr Sweeney, the accounts are aimed at providing "transparency" and use publicly available data from the Federal Aviation Administration.

"I think it's important to note that nowhere do I intend for harm, I simply share the facts," he told NBC News.

"I actually think Swift has some good songs," he added.

Swift's movements this weekend are tipped to be more closely watched than ever, as fans try to see whether she'll be making the journey from her fourth and final show at Japan's Tokyo Dome on Saturday straight to Las Vegas, where the Kansas City Chiefs will play the San Francisco 49ers on Sunday.

Experts say Swift could complete the gig and arrive in Las Vegas with enough time to attend the game if she uses her jet.

She has faced criticism over the carbon footprint from her use of private jets in the past, though her representatives have previously said she uses offsetting through the purchase of carbon credits to compensate.

"Taylor purchased more than double the carbon credits needed to offset all tour travel," her publicist said before the start of her recent Eras Tour.