While it has always been difficult to avoid adverts for prostitutes in sites such as phone boxes, the rise of social networking has made it even easier to access explicit content.
An investigation by The Times revealed that prostitutes and sex agencies openly solicit for customers on sites such as Facebook and Twitter, the Daily Mail reported.
The pages, which can be created by anyone and do not require approval by the sites' management, provide details such as addresses, phone numbers, prices and the specific services.
Some are disguised as adverts for models or masseuses, but betray their true purpose with phrases such as: "Bianca can satisfy physically like no other provider can."
One was even offering a give away competition to win a free home session valued at 150 pounds.
Other adverts appeared to be searching for young women to work as prostitutes, promising they can "earn about 9,000 pounds a month and live in good apartments in Central London."
Facebook removed a number of the offending pages after the newspaper drew attention to them.
However, the web giant headed by Mark Zuckerberg admitted that it shuts down pages only if users of the site report them as being offensive.
When Twitter was alerted to adverts for prostitution on its site, it refused to remove them unless someone could prove a breach of the law had taken place.
Gavin Shuker, chairman of the all-party parliamentary group on prostitution, promised to investigate the posts.
He said that current legislation on prostitution was a "Swiss cheese" which "sends mixed messages."
Police have previously been advised to monitor online advertising in order to crack down on sex trafficking, but they rarely take any action against individual sex workers or their clients.
Facebook is believed to be used by millions of British schoolchildren - although the official age limit is 13, it is easy to circumvent the rules.
Child abuse expert Jim Gamble warned that social media posts about prostitution could be a "gateway" into paying for sex, as it encourages negative images of sexuality.