Three Melbourne men who paid to avoid trial for gang-raping a 17-year-old in Croatia have been labelled "gutless" and "disgusting" via a social media campaign intended to support them.

Dylan Djohan, 23, Ashwin Kumar, 23, and Waleed Latif, 21, pleaded guilty but struck a deal with Croatian prosecutors, requiring them to pay just over $30,000 to the Norwegian girl after her rape in a late-night bar.

The payment, which was accepted by the victim, outraged women's rights campaigners.

Friends of the men fuelled the anger yesterday, posting their support on social media with the hashtag #istandwiththeboys.

In a series of tweets and Facebook messages, friends of the men reportedly claimed the payment was a case of extortion and even labelled the victim a slut.

But Twitter users have condemned the men's actions, using the same hashtag intended to defend them.

User Scott tweeted: "Reading some of the #istandwiththeboys tweets makes me disgusted to be Australian".

"Rapists deserve jail time not buying freedom," Norwegian Trondheim Hatter commented.

Joel was more vocal: "Ha! The day I support 3 gutless rapists who were so cowardly they paid off their victim to avoid jail ... Is the day I die".