Ticketmaster has released a statement apologising to Taylor Swift and her fans following a ticketing debacle earlier in the week. 

Pop superstar Swift said on Friday it was "excruciating" for her to watch fans struggle to secure tickets for her upcoming US tour after she had been assured Ticketmaster could handle large demand.

Many people hoping to land seats for Swift's Eras tour, to her first concerts in five years, said they waited hours and were repeatedly kicked off the Ticketmaster website during pre-sales this week.

Swift said on Instagram it was "excruciating for me to just watch mistakes happen with no recourse".

She said she was "not going to make excuses for anyone" because her team had been assured multiple times by ticket sellers that they could handle a surge in demand.

Ticketmaster offered seats for most shows on the 20-city, 52-date US stadium tour from March through August.

Ticketmaster said it wanted to apologise to "Taylor and all of her fans — especially those who had a terrible experience trying to buy tickets".

The company said it is working to shore up its technology "for the new bar that has been set by demand for the Taylor Swift's Eras Tour".

SeatGeek sold tickets for a handful of performances in Texas and Arizona and also reported long waits, urging fans to "please be patient".

SeatGeek did not immediately respond to requests for comment.

Earlier in the week, Ticketmaster said it experienced unprecedented interest in Swift's tour from millions of people and worked quickly to resolve technical problems during the pre-sales.

It cancelled sales to the general public scheduled for Friday.

Swift said it was "truly amazing" 2.4 million people had bought tickets, "but it really pisses me off that a lot of them feel like they went through several bear attacks to get them".

The Anti-Hero singer said she was "trying to figure out how this situation can be improved in the future".

Ticketmaster has angered artists and fans periodically for decades.