BBC director-general George Entwistle offered a "profound and heartfelt apology" to the alleged victims of Sir Jimmy Savile's sexual abuse as he announced that two inquiries would be launched.

One will look into whether there were any failings over the handling of an abandoned Newsnight investigation into the late DJ and broadcaster. A second independent inquiry will look into the "culture and practices of the BBC during the years Jimmy Savile worked here", Mr Entwistle said.

Speaking at a press conference at New Broadcasting House in central London, Mr Entwistle said: "As the director-general of the BBC I have made clear my revulsion at the thought that these criminal assaults were carried out by someone employed by the BBC and that some may have happened on BBC premises as well as, we now discover, in hospitals and other institutions across the UK."

He continued: "I have one thing to repeat - that is a profound and heartfelt apology on behalf of the BBC to every victim. It is the victims, these women who were subject to criminal actions, who must be central in our thoughts."

Since ITV screened a documentary in which five women alleged they were abused, new claims about Savile's predatory behaviour have emerged on a daily basis.

Scotland Yard is pursuing 340 lines of inquiry in the Savile abuse case involving 40 potential victims, the force revealed. So far 12 allegations of sexual offences have been officially recorded but this number is increasing, Scotland Yard said.

Metropolitan Police detectives are in contact with 14 other forces as the number of allegations against the former DJ continues to rise.

Speaking about the inquiry into the "culture and practices" at the BBC during the Savile years, Mr Entwistle said: "It will examine whether that culture and those practices allowed him or others to carry out the sexual abuse of children. It will also examine whether the BBC's child protection, whistle-blowing and bullying and harassment policies and practices are now fit for purpose."

Mr Entwistle said he wanted to ensure "nothing of this kind could ever happen again at the BBC" as he revealed two "independent figures" would lead the inquiries. They will be commissioned by the BBC executive board, chaired by Dame Fiona Reynolds. "These will be forensic but also soul-searching examinations," Mr Entwistle said. "Our audience's trust in us is paramount. We will do everything in our power to maintain that trust and we will do that by holding ourselves to account fully and openly, as we have always done and as our audience expect."

The second inquiry will look at whether there were any failings in the BBC management in the decision not to air the Newsnight investigation, he added. "Despite our efforts to make our belief that the decision to drop the Newsnight investigation was taken properly for sound editorial reasons, people have continued to speculate. This is damaging to the BBC and is a cloud of suspicion which cannot be allowed to continue."