Revelations that politicians allegedly murdered and raped young boys is "only the tip of the iceberg" in the Westminster historic child abuse scandal, Theresa May has warned.
The UK Home Secretary expressed dismay that institutions designed to protect children failed in the past and said she was determined to bring those guilty to justice, whatever their position.
Mrs May also gave her strongest indication yet that the Government will miss its target to bring annual net migration below 100,000, saying reaching the goal by next May was "unlikely".
The comments came on a weekend in which Mrs May appeared on Radio 4's Desert Island Discs and on BBC One's The Andrew Marr Show – the corporation's flagship Sunday current affairs programme.
In recent weeks new allegations have emerged suggesting Tory MPs murdered and abused boys as part of an establishment paedophile network in the 1970s and 80s. Police are investigating the claims.
Mrs May told The Andrew Marr Show: "How was it that in the past, but continuing today, the very institutions of the state that should be protecting children were not doing so?"
"Why was it that these abuses were able to take place and that nobody was brought to justice as a result of that. We must as a society, I believe, get to the truth of that and because I think what we’re seeing is frankly - what we’ve already seen revealed - is only the tip of the iceberg on this issue.”
Earlier in the same programme the Metropolitan Police commissioner Sir Bernard Hogan-Howe said dozens of officers were investigating historic Westminster child abuse claims but admitted the police were struggling to locate old dossiers of evidence.
“First of all we are taking it seriously. We have got 40 detectives looking into these relatively new claims, and there are a series of claims over a relatively long period of time and not all of them are linked, although in the public’s imagination they may be, in that it is child abuse," Sir Bernard said.
"We have now had more recently this discussion or these claims about murder and of course that makes it even more serious."
He said locating old evidence was a "real challenge", adding: "You have to rely on the index and if the index is wrong you can't find it, or you look in the wrong box."
On the Government's net immigration target, Mrs May said: "It is of course unlikely that we’re going to reach the tens of thousands by the end of the Parliament."