Police in Northern Ireland have expressed concern after almost 80 children and teenagers fell victim to online criminals.
The most common offences included harassment. Officers urged parents to learn enough about the internet to keep their children safe.
The explosion of social networking sites has increased the opportunity for interacting with potentially harmful individuals.
Police Service of Northern Ireland (PSNI) detective chief inspector Douglas Grant said: “We are concerned about the number of younger victims in the provisional figures we have released.”
Between October last year and April, the force recorded 429 computer offences, 78 involving victims aged 19 or under.
Mr Grant added: “The internet is a fantastic resource for learning, communicating and entertainment but, on the down side, it also provides opportunities for some individuals or groups to harm or abuse people - particularly young people.”
The two most common offences out of the 429 were fraud and harassment. There were 45 sexual incidents, 32 threats to kill and seven reports of blackmail.
A break down of types of victim showed that 78 were aged 10-19, 113 aged between 20 and 29 and 71 aged between 30 and 39.
A total of 31 offenders have been detected by police over the seven-month period.
Research by communications regulator Ofcom last year indicated that around half of parents of 5- to 15-year-olds felt their children knew more about the internet than they did.
It suggested parents need continuing support to build their own skills and confidence because of the fast pace of technological change and the ease with which children can embrace and explore new technology.
A special website - www.GetSafeOnline.org - has been launched. Officers are visiting schools and giving talks about keeping safe online.
Mr Grant added: “We will be providing basic material to encourage parents and children to become aware of the risks and do something about it together, what we call getting switched on.”
The warning comes as British police investigating the death of a Scottish teenager who took his own life after being blackmailed by strangers online have been involved in a major international operation targeting cyber-crime in the Philippines.
Officers have said common sense steps can be taken to minimise the risk and threat from online criminals.
These include installing good anti-virus software, not using passwords which are easy to guess and not posting personal information or images you would not want family or friends to see.
The National Crime Agency is set up to tackle problems like internet crime, which can easily cross borders, on a UK-wide basis. Northern Ireland has not fully signed up to the body, known as the British FBI, because of accountability concerns.