The BBC is "falling short" on its obligations towards older women and minority communities, the head of the media watchdog has said.
Sharon White, Ofcom's chief executive, said the corporation is "not doing as good a job as it should be" in relation to certain groups in society.
Drawing on Ofcom research into diversity in public service broadcasting (PSB), Ms White told the Financial Times: "We have done an awful lot of research, talking to people in Scotland, Wales and Northern Ireland, and they do not feel the stories being told sufficiently reflect their stories.
"On minority communities, older women, it is not doing as good a job as it should be.
"There is a gap there and it is a gap I would like to see closed over time."
She added: "All the research we have done broadly shows that people think the BBC is doing a good job. But it is falling short on those stories that reflect all of the nation and its communities."
Earlier this year, the BBC pledged that women would make up half of its workforce on screen, on air and in leadership roles by 2020.
A BBC spokesman said: "Ofcom are clear that the research they are referring to is for all PSBs not just the BBC, but despite that we're always happy to debate what we do on screen and we don't think any broadcaster does better in representing older women than the BBC.
"We're proud of the fact that the BBC of today has a huge range of women presenters across TV and radio including Mary Berry, Carol Klein, Anne Robinson, Felicity Kendal, Joan Bakewell, Jenni Murray, Mary Beard, Gloria Hunniford, Angela Rippon, Julia Somerville and Kirsty Wark."
The BBC will be regulated by Ofcom from next year, the first time an independent organisation has governed the corporation, replacing the internal BBC Trust.
Ofcom already monitors the rest of British television, radio and video on-demand platforms, as well as telecoms, the radio spectrum and postal services, and is accountable to Parliament.
Television programmes regulated by Ofcom must comply with the rules and principles of the Ofcom Broadcasting Code, which includes directives on taste and decency standards, fairness and privacy. Decisions about breaches of that code are made by a board.
The BBC is currently regulated by the trust, its executive board and Ofcom.