An unprecedented public inquiry into child sex abuse in Britain is to focus first on the Anglican and Catholic churches,  its chairman said.

Justice Lowell Goddard said the five-year inquiry is the most wide-ranging ever of its kind in England and Wales and will consist of 12 separate investigations that will also focus early on local authorities such as Lambeth, Nottinghamshire and Rochdale.

It will also look into public institutions and people of "public prominence".

She said: "To run 12 investigations in parallel represents an organisational challenge that is unprecedented in a public inquiry in the United Kingdom. We are determined to succeed." She said she was confident her inquiry will "give a voice to victims and survivors."

She and her team will investigate Medomsley Youth Detention Centre in County Durham, Cambridge House boys' home and Knowl View in Rochdale and examine allegations made against the late Liberal MP Cyril Smith. Goddard added that the inquiry would investigate high-profile allegations of a child sex abuse ring operating in Westminster, and abuse cover-ups.

Regional truth centres for victims will be set up next year.

She said: "The investigation will focus on high-profile allegations of child sexual abuse involving current or former members of parliament, senior civil servants, government advisers and members of intelligence and security agencies.

"It will consider allegations of cover-up and conspiracy and review the adequacy of law enforcement responses to these allegations."

Catholic Benedictine congregations and the Church of England's Chichester diocese are among the religious organisations that she will investigate.

Goddard will take in the case of jailed Anglican bishop Peter Ball, who abused 18 young men over 20 years, to see whether anyone tried to save him from justice.  She will look at the armed forces, Foreign Office, the British Council and other institutions. Each of the 12 inquiry strands will have public hearings. 

The Catholic Church, which has also had two earlier independent inquiries into child sex abuse, welcomed the inquiry and announced that it had set up a special council of its own to help, to be chaired by Baroness Nuala O'Loan. She said: "The role of the council is to facilitate and ensure the proper response to the inquiry, which has the Church's full support. We look forward to hearing their specific requests and will ensure full co-operation with their deliberations."

The Church of England also welcomed the inquiry.