Online giant Amazon has indicated it is investigating claims by the Wall Street Journal that some employees are accepted bribes to disclose confidential data giving sellers using its marketplace a competitive advantage.

The US newspaper published an investigation suggesting that employees working through brokers, have sold internal sales data, the email addresses of product reviewers, and the ability to delete negative reviews and restore banned accounts.

“We are conducting a thorough investigation of these claims,” an Amazon spokeswoman said. She said the company would pursue penalties against employees who violated its code of conduct and ethics and against merchants who disregarded its policies.

“We implement sophisticated systems to restrict and audit access to information. 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.

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

The Journal’s reporting found the practice was a particular problem in China, and that Amazon had begun investigating in May when it became aware of incidents there.