Who says you can't buy friends? An Australian online marketing company is selling friends and fans to Facebook members after offering a similar service to Twitter users.

Advertising, marketing and promoting company uSocial said it was targeting social networking sites because of their huge advertising potential.

"Facebook is an extremely effective marketing tool," Leon Hill, uSocial CEO, said in a statement.

"The simple fact is that with a large following on Facebook, you have an instant and targeted group of people you can contact and promote whatever it is you want to promote," he added.

"The only problem is that it can be extremely difficult to achieve such a following, which is where we come in.

The company offers packages for Facebook, the world's number one social networking site, that start at 1,000 friends up to 10,000 friends at costs ranging from $177 to $1,167.

"All we do is send them a welcome message or friend request from the client. If they decide to go ahead and add that person as a friend or a fan then they will; if not, then they won't," Hill told Australian media.

Facebook is now the world's fourth-most visited website.

The company, which counts venture capitalist Peter Thiel, Accel Partners, Microsoft Corp and Russian Internet investment firm Digital Sky Technologies among its investors, has more than 250 million registered users.

But uSocial's packages are not without controversy.

According to some Australian websites, Twitter tried to shut uSocial down, accusing it of spamming members, while the Los Angeles Times reported that Digg.com, a website where people vote for their top news stories or websites, has also tried to shut down uSocial because it sells votes.