A group from Brazil has managed to unlock Apple's iPhone 3G handset just days after its release.

The unlocked iPhone is displayed and demonstrated in an online video on a Portuguese-language news blog.

An unlocked iPhone can be used with any Sim card and service provider.

IPhone user Bruno MacMasi said in an interview with Gizmodo that the unlocking process involved modifying the Sim hardware so that the International Mobile Subscriber Identity can be overwritten and removed from the original network.

A similar process was used to unlock the original iPhone last year.

Separately, a group of researchers known as the iPhone Devteam has released the first 'jailbreak' software releases for the iPhone 3G and the iPhone 2.0 software update.

The 'jailbreak' term refers to the process of removing the software controls which prohibit users from installing software outside of the iPhone App Store.

The group, which has asked not to be linked to directly for bandwidth purposes, is currently offering a software utility which automatically performs the jailbreak process.

Unlocked and modified handsets have been an issue ever since Apple first released the iPhone. Users initially were eager to remove the strict controls over installing software and run the handset with other carriers.

While the iPhone App Store has allowed for the distribution of third-party applications, there remains a dedicated group of users wishing to run older third-party applications and software which have not been approved for the Store.

Apple has attempted to remain relatively neutral on the matter. The company said that, while the jailbreak processes will void the warranty and possibly cause damage to the phone when new updates are installed, no special efforts will be made to deliberately disable or 'brick' hacked iPhones.