Facebook is to offer personalised profile URLs on a first-come, first-served basis.

Until now profile pages on the social networking site were assigned a random number, but in what may be seen as a bid to compete with micro-blogging service Twitter, Facebook profile URLs will now take the form of www.facebook.com/ followed by a username of your choice.

"We're planning to offer Facebook usernames to make it easier for people to find and connect with you," the social network said on its blog.

From 5:01am on June 13, Facebook account holders will be able to visit Facebook's username page where they will be given a number of username options to chose from.

"Facebook usernames will be available in basic text forms, and you can only choose a single username for your profile," Facebook said.

Facebook said usernames must be a minimum of five characters and can only contain letters, numbers or a full stop. In a bid to stop 'squatting'. The social network said that anybody that signed up for a profile after May 31 may not be able to sign up for a username immediately.

The social network also warned that users should "think carefully about the username" as "once it's been selected, you won't be able to change or transfer it".