A New Zealand fugitive who is wanted on sex trafficking charges has been arrested in Spain, the FBI says.

Michael James Pratt, from Christchurch, was arrested on Wednesday in Madrid. He was staying in a hotel under a false identity, Reuters reported.

Pratt was on the FBI’s list of Ten Most Wanted Fugitives, a list which has previously included serial killer Ted Bundy and 9/11 mastermind Osama Bin Laden.

An FBI statement said Pratt was wanted on 19 charges including sex trafficking, production of child pornography, sex trafficking of a minor and money laundering. He has been on the run since 2019 and authorities had offered US$100,000 for information on him.

Pratt was being held by Spanish authorities while the United States sought an extradition order.

The charges against him related to a website he ran called GirlsDoPorn. It was alleged that he tricked women into becoming online porn stars, and used the pornography to rake in earnings of $US17m ($30m).

Spanish police announced the arrest on Twitter, publishing a video of officers handcuffing a man and searching him.

Pratt, who grew up in Christchurch, moved to the United States in 2009.

Prosecutors in the US say that Pratt, who ran the now-defunct websites for around seven years, coerced hundreds of women to appear in pornographic videos under false pretences.

They allege that Pratt – along with another New Zealander and accomplice Matthew Wolfe and others – lured unsuspecting women with adverts for clothed modelling gigs.

The women, many of whom were struggling financially, were offered between US$3000 and US$5000 as payment, as well as an “all expenses” trip to San Diego.

“They repeatedly assure the victims they will never publish the videos online and that the women will remain anonymous,” according to a civil claim which has subsequently been successful in the US courts.

New Zealander Michael James Pratt has been named on the FBI's Top 10 Most Wanted Fugitives list. Photo / Supplied

When it was revealed that the job involved filming for adult videos, the victims were led to believe that the footage would only be distributed to private customers in far-off places like Australia or New Zealand.

However, the videos soon showed up online, which prosecutors say was always the plan of Pratt, Wolfe and a third individual, an American man named Ruben Andre Garcia, a porn actor and producer already sentenced to 20 years in prison.

If the women ever changed their minds about filming or completing the scenes, they were threatened with legal action, or told their flights home would be cancelled, or the footage would be sent to friends or family.