Facebook has started charging its UK users up to £10 to contact celebrities, public figures or other users outside their network as part of its efforts to prevent users being flooded with spam messages.

Initially launched as a trial scheme in the UK, the social network’s new system is aimed at private messaging and create a sliding scale of payments to celebrities.

According to the social networking site, the charging fee structure differed as per the number of factors that include the number of followers and a secret fame algorithm.

Facebook said in a statement the system of paying to message non-friends in their inbox is designed to prevent spam while acknowledging that sometimes you might want to hear from people outside your immediate social circle.

"We are testing a number of price points in the UK and other countries to establish the optimal fee that signals importance," the social networking site said.

Earlier, Facebook allowed its users to send messages from their account to strangers for free and has recently started storing messages in a less noticeable ‘other’ message box, while leaving the inbox only for friends and family.