After the New York Times columnist Nicholas Kristof claimed that the website contained images of child abuse and nonconsensual sexual harassment, Visa and Mastercard said they would investigate their financial ties to MindGeek, the parent company of the adult website Pornhub.
In a statement, Visa said it was "actively engaging with the relevant financial institutions" to investigate the allegations and with MindGeek.
Visa, which deals with 61 million retailers and in a year transfers almost $12 trillion in money through the financial system, said it was "vigilant" to exclude illicit businesses from its network. Banks serve as intermediaries for payment firms and businesses such as Visa and Mastercard.
"If the site is identified as not complying with applicable laws or acceptable use policies and subscription standards of financial institutions, they will no longer be able to accept Visa payments," the statement said.
Mastercard also said that MindGeek's bank was investigating the claims against Pornhub. "We will take immediate action if the claims are substantiated," Mastercard said in a statement. "Our strategy is to ask the acquirer to terminate the partnership when we detect criminal activity, unless an appropriate enforcement plan is placed in place.
Every year, nearly seven million videos are posted on Pornhub, and although the vast majority of them presumably represent consensual acts, Mr. Kristof wrote that many do not. He announced that the website had found images of teenage girls who had been victims of abuse and trafficking.
Criminals were prosecuted for the assaults in each case, but Pornhub escaped responsibility for distributing and profiting from the videos," Mr. Kristof wrote."
"Pornhub denied the allegations and stated that it was "unambiguously committed to combating content of child sexual exploitation and developed a robust, industry-leading trust and protection policy to identify and remove illicit material from our community.
Some other payment providers do not allow adult content platforms to be used for their services. American Express has a policy against "adult digital content" using its cards.
And PayPal, including videos, photographs and subscriptions, "prohibits all account holders from buying or selling sexually oriented digital goods." PayPal barred Pornhub and the website's video providers from making and receiving payments via PayPal last year. After that, Pornhub added new payment options, including Tether, a cryptocurrency centered on the blockchain.