Amazon is investigating allegations that some of its employees have offered to leak confidential information and delete negative product reviews in exchange for money.

According to a Wall Street Journal report on Sunday, Amazon staff members are peddling internal data and other advantages that independent merchants can use to try to get higher rankings for their products in searches on the site. The practice is “particularly pronounced in China,” the article said.

An Amazon spokeswoman told CNN that the company has launched an investigation into the claims.

“We hold our employees to a high ethical standard and anyone in violation of our code faces discipline, including termination and potential legal and criminal penalties,” she said.

Brokers for Amazon employees in the southern Chinese city of Shenzhen offered internal sales metrics and reviewer email addresses to independent sellers for payments of between $80 and $2,000, according to the Journal report. The brokers were also proposing to delete negative reviews and restore banned accounts, it said.

Amazon has “sophisticated systems to restrict and audit access to information,” the company spokeswoman said, adding that it would also punish sellers who break its rules.

“We have zero tolerance for abuse of our systems and if we find bad actors who have engaged in this behavior, we will take swift action against them, including terminating their selling accounts, deleting reviews, withholding funds, and taking legal action,” she said.

The Journal reported that Amazon was investigating several incidents, including some involving employees in the United States.

The e-commerce giant has had issues with its product reviews dating back years.

In 2015, the company sued more than 1,000 people who were “misleading Amazon’s customers” by selling “fake reviews of products,” according to a complaint. That lawsuit targeted account holders on Fiverr.com, a marketplace for odd-jobs where “gigs” are sold for $5 and up.