The BBC is understood to be investigating a radio presenter who has been accused of sexually assaulting at least eight female colleagues.
Four of the women have submitted formal complaints about the male presenter, who cannot be named for legal reasons, MailOnline reports. The other women are said to be "too scared" to report him because of potential damage to their careers.
He is accused of approaching female colleagues from behind and groping them from underneath their skirts. The alleged assaults took place over the last six years, at informal events where other BBC staff were present.
Bulford wrote in an email: "There’s been a lot of press coverage and comment recently about bullying and harassment in the entertainment industry, and more broadly. Tony Hall [the director-general] and I have written to you a number of times on this.
"We have a duty of care to protect you – one we take extremely seriously. I just want to remind you what to do if you want to raise any concerns. Please be assured that we will continue to handle any issues raised sensitively."
Asked about the investigation into the radio presenter's alleged sexual assaults, a BBC representative said: "We can’t comment on individuals but treat any allegations seriously and have processes in place for investigating them."