Amazon has hired an outside law firm to investigate widespread gender discrimination claims in part of its cloud computing division, the company said in an email to employees last weekend.

The investigation came in response to a request made by a group of employees of Amazon Web Services’ Professional Services group, an organization called Prosev, which helps companies adopt cloud computing. In the petition the employees accused the department of gender bias and bullying. The Washington Post, which reported the investigation earlier, said more than 550 employees had signed the petition.

Adam Selipse, the new chief executive of AWS, responded to the email, which was addressed to petition leaders.

“We have maintained an external pay firm to investigate and understand any inappropriate behavior that you or others have experienced or witnessed,” he wrote. “This pay firm is experienced and purposeful and I will personally review their independent findings, which will help guide any further action.”

Amazon is heavily recruiting at AWS, the largest provider of cloud computing. The industry is largely dominated by men. About 23 percent of Amazon’s senior leaders at the company’s data show are women.

In May, five women, including one working at ProServe, accused the company of various racial and gender discriminations, the company denied.