David Cameron has slapped down a public health expert who asked for a debate on lowering the age of consent.
Professor John Ashton said the move would "draw a line in the sand" against people having sex at 14 or younger.
Ashton, the president of the Faculty of Public Health, told the Sunday Times that "confused" messages were being sent to young people by society.
But his comments drew a response from Downing Street, saying the minimum age was 16 "to protect children" and that there were no plans to lower it, the BBC reported.
Deputy Prime Minister Nick Clegg also rejected the call. He told Andrew Marr he was worried about the sexualisation of children, adding: "Yes there is a problem, yes we need a debate...but this is not the answer."
Official figures suggest up to a third of teenagers have sex before the present age of consent of 16.
Ashton said the move would also make it easier for 15-year-olds who are in sexual relationships to obtain contraception or sexual health advice from the NHS.
"Because we are so confused about this and we have kept the age of consent at 16, the 15-year-olds don't have clear routes to getting some support," he said.
"My own view is there is an argument for reducing it to 15 but you cannot do it without the public supporting the idea and we need to get a sense of public opinion about this.
"I would not personally argue for 14 but I think we should seriously be looking at 15 so that we can draw a line in the sand and really, as a society, actively discourage sexual involvement under 15. By doing that, you would be able legitimately to organise services to meet the need."
The Faculty of Public Health, part of the Royal Colleges of Physicians, gives advice to ministers and civil servants although it is independent of government.
David Tucker, head of policy at the NSPCC, said he would be happy to have a debate on the issue but said he would want to see the evidence for Prof Ashton's claims.
"Has there really been a significant change in the amount of young people having sex over the past 20 or 30 years? If it has changed, then is reducing the age of consent the most sensible way to deal with it?" he told the Sunday Times.