The UK-wide National Crime Agency (NCA) last year dealt with 20 reports of Scots being raped after meeting someone through a dating website, compared with six in 2014.
Most attacks took place during the first face-to-face meeting after making contact online. Most victims were women.
The figures relating to crimes in Scotland emerged after a former Territorial Army officer, Philip Donegan, 50, from Glasgow, was last week jailed for eight years for raping two women he met on dating site match.com.
Experts say the figures show the need to be cautious and follow safety advice but also point out the rise indicates more people are going online to meet partners. An estimated one million Scots are registered with online dating sites.
The NCA’s serious crime analysis section works to identify potential serial killers and rapists at an early stage by collating reports of the most serious incidents from police forces across the UK. It was set up in the wake of the case of Yorkshire Ripper Peter Sutcliffe, who murdered 13 women in the north of England.
The NCA received six reports of allegations of rape initiated through dating sites in Scotland in 2014. The following year the figure was ten and in 2016 it was 16.
Last year 20 cases were reported.
Sean Sutton, NCA head of national investigative capabilities, said a major reason behind the rise in cases was the larger numbers of people using dating sites.
He said: “No one will be surprised that the internet and its capabilities, while making life very much easier and simpler for us all to navigate, means that offenders will also use that ease of use and simplicity to identify potential victims.”
But he said incidents were likely to be vastly under-reported, with anecdotal evidence suggesting many victims of dating site sex attackers are unwilling to go to police.
Police Scotland figures show there were 87 rapes in 2016-17 when the victim met their attacker online through social media or internet dating – up 24 per cent on the previous year.
Sandie Barton, of Rape Crisis Scotland, said the charity’s helpline received calls about people targeted through dating websites but cautioned against “fear-mongering”.