Rdio, the online music streaming service that lets customers listen to more than 18 million songs without ads or interruptions, has announced they are offering a number of international customers the same six months of free music streaming that users in the US have enjoyed since October 2011.

The service will offer its six month free trial in the United Kingdom, Australia, Belgium, Canada, Denmark, Estonia, Finland, France, Netherlands, New Zealand, Norway, Portugal, Spain, and Sweden, according to a spokesperson speaking with CNET via email. Those with access to the free trial will be able to stream music, create playlists, use a discovery engine and even share listening habits on social networks.

Unsurprisingly, the goal is to attract more international users and heat up competition. Services like Pandora and Spotify already have a solid following that we suspect Rdio would like to duplicate.

Ultimately Rdio would like to add more paying customers to their portfolio. Pricing starts at $4.99 per month for unlimited web streaming while an investment of $9.99 monthly will get you unlimited web, mobile, and offline listening. Pricing will of course differ by country but things seem right in line with competing services with regards to pricing structure.

The service launched in the US back in August 2010 and has since expanded to include Facebook support. The service was founded by Niklas Zennstrom and Janus Friis - the two people behind music sharing service Kazaa (as well as Skype and Joost).