Andrew Tate and his brother Tristan Tate, the online influencers known for their misogynistic views, were arrested by U.S. Marshals on Saturday in Miami in connection with an investigation into sex crimes in England, law enforcement officials in the country said.

The brothers were detained “pending ongoing legal proceedings,” according to a statement from the police in Bedfordshire, a county outside London. The police have been investigating the pair alongside other British and international law enforcement agencies for alleged crimes that include rape and sex trafficking.

The arrests were the latest twist in a yearslong legal saga for the brothers, who came to symbolize the manosphere while being dogged by accusations of abusing women.

The two men, and their lawyers, had previously denied the abuse allegations against them. Joseph McBride, an attorney for the brothers, said in a statement on Saturday that they “are innocent.”

The new charges stem from alleged offenses against four more victims that took place between July 2010 and August 2017, Britain’s Crown Prosecution Service said in a statement on Sunday after the arrest.

“These charging decisions followed receipt of a further file of evidence from Bedfordshire Police and bring the total number of alleged victims in this case to seven,” Malcolm McHaffie, head of the Special Crime Division at the service, said in the statement.

The statement from Bedfordshire Police added that the case grew “against both men in relation to reports of offences made in both Bedfordshire and Hertfordshire,” counties that are north of London.

“There is no place for male violence against women and girls in Bedfordshire and we continue to work tirelessly to support victims and investigate all reports made to us,” the police statement said.

Mr. McBride took aim at the authorities in Britain and United States in a statement posted on social media, claiming that a pending defamation lawsuit in Florida would clear their names.

“We are confident that once a competent judge sees the facts, and once the Department of Justice confronts this egregious abuse of its own authority, Andrew and Tristan Tate will walk free,” Mr. McBride said.

The brothers, who were professional kickboxers, face dozens of new charges in the case.

British prosecutors said in their statement that the new charges against Andrew Tate, 39, include seven counts of rape; three counts of sex trafficking; three counts of assault; and 19 more charges relating to sexual images of children and “extreme pornography.”

Tristan Tate, 38, faces two new charges of rape; one count of sexual assault; and three counts of sex trafficking.

British prosecutors are seeking the brothers’ extradition. They were arrested by U.S. Marshals with a sealed warrant, spokesman Brady McCarron said in a statement.

Andrew Tate had been advertised as a co-host for a bare-knuckle boxing event on Saturday night in downtown Miami.

The brothers had been under investigation in Romania over allegations that they coerced dozens of women, including a 17-year-old girl, into pornography, and that Andrew Tate was having sex with a 15-year-old. They returned to the United States last year after prosecutors lifted restrictions on their travel.

In March, Hertfordshire police reopened an investigation into sex-crime allegations against Andrew Tate, which were brought by three women who had separately accused him of sexually assaulting them. The three women, and a fourth, were also suing him at the High Court in London over the allegations.

Maia Spoto contributed reporting.