Paedophiles will be handed the same treatment as terrorists under a crackdown on child abuse to be included in the Queen's Speech.
David Cameron said he wanted to close a loophole that allows sexual predators to produce and possess "manuals" giving tips on how to identify victims, groom them, and evade capture.
In future, they will face the same kind of sanctions as extremists who download guides to bomb-making.
The issue came to light after GCHQ and the National Crime Agency found online examples of the guides in the chaotic part of cyberspace known as the "dark web".
The Prime Minister told the Sunday Times: "It's completely unacceptable that there is a loophole in the law which allows paedophiles to write and distribute these disgusting documents.
"I want to ensure we do everything we can to protect children - and that's why I am making them illegal."
The new law is expected to be in force by the time of the general election next year, and could be implemented in an amendment to the Obscene Publications Act 1959, according to the newspaper.
The Terrorism Act 2000 outlawed terrorist training manuals.
The move was announced after it emerged that a paedophile teacher drugged and abused up to 60 boys as young as 10 at a British private school.
William Vahey, who taught history and geography at Southbank International School in London between 2009 and 2013, committed suicide last month as FBI agents closed in.
Peter Wanless, chief executive of the NSPCC, said: "We would welcome any change in legislation that tackled offenders using the dark web and other online areas to distribute these vile 'how to' guides on child abuse.
"But far more needs to be done - and fast - to tackle online child sex offenders. The Government must ensure police have the investigative capacity to infiltrate and disrupt the networks of offenders hidden online, so these disgusting criminals are brought to justice."
Shadow home office minister Diana Johnson said: "The Government isn't going far enough or fast enough to prevent online child abuse.
"It is absolutely right that these 'manuals' are to be banned, but the fact that online guides for abusing children are currently legal shows how ill-suited current legislation is for protecting children online.
"At present online abuse is increasing while the number of arrests is falling. Over the past three years we've seen a 60% decline in the number of arrests made by CEOP (the specialist police unit looking at online abuse) while referrals rose 14% last year.
"Ministers are slowly reacting to new practice adopted by online abusers when they should be taking a proactive approach which recognises the unique nature of online abuse and the scale of the problem.
"There is much more that could be done including updating current legislation and ensuring online abuse is a priority for the National Crime Agency.
"The Government also need to look at the broader issues of how we regulate dangerous online content and prevent children accessing adult content.
"The Prime Minister promised to make online restrictions equivalent to off-line restrictions but he has not come close to implementing this."