A BBC source has claimed that former BBC presenter Jill Dando compiled a dossier of claims that a paedophile ring was operating within the Corporation – but the allegations were dismissed by senior management.

The report states that Dando, who was murdered on her doorstep in south-west London in 1999, was told that paedophiles were operating within the BBCs in the 1990s. Several female colleagues also alleged that they were sexually harassed or assaulted by male BBC colleagues.

Dando reported the allegations to senior management at the BBC, the source claims, but her findings were not followed up as she "was not an investigative journalist". Bosses at the BBC – who have already been rocked by revelations about sexual predator Jimmy Savile – just "didn't want to know".

The source, a retired BBC worker, told the Daily Star that Dando had revealed some "big names" who were accused of sexual offences.

"I don't recall the names of all the stars now and don't really want to implicate anyone but Jill said they were surprisingly big names.

"I think she was quite shocked when told about images of children and that information on how to join this horrible paedophile ring was freely available.

"Jill said others had complained to her about sexual matters and that some fellow female workmates also claimed they had been groped or assaulted. Nothing had been done and there seemed to be a policy of turning a blind eye."

The source told how female colleagues went to Jill, who was then one of the best-known faces on TV and presenting BBC programmes including Crimewatch and Holiday, passed a dossier of the reports to senior management, but the claims were not investigated and female colleagues didn't pursue the complaints for fear of damaging their careers.

"She compiled a file of complaints but she was not really an investigative journalist, just a presenter. She passed the information to someone else and they gave it back. No one wanted to know... She gave a file to senior management. I don't think she heard any more.

"Other women who complained told Jill they didn't want to risk their careers by making official statements against individuals as they would lose their jobs and that bosses seemed to ignore it.

"We all decided the best way was to keep our heads down and to always try to go somewhere with a colleague."

Dando was shot dead on the doorstep of her home in Fulham in 1999. Barry George was wrongly convicted of her murder in 2001 and his conviction was quashed in 2008.