The legal battle between Nokia and Apple has stepped up yet another rung with the news that Apple has now filed a patent-infringement complaint against Nokia with the ITC.

Apple, as did Nokia before it, is petitioning the US International Trade Commission in Washington to try and block imports of its rival's products.

As a recap for those new to this legal saga, Nokia sued Apple over patent infringements in October 2009, Apple then sued Nokia back 2 months later on roughly the same charges.

Nokia then followed up with an ITC complaint, trying to get Apple in trouble with the Commission in December before filing a further suit against Apple stating it's infringing several "implementation patents".

"Nokia will study the complaint when it is received and continue to defend itself vigorously", a Nokia spokesperson told Bloomberg.

"However this does not alter the fact that Apple has failed to agree appropriate terms for using Nokia technology and has been seeking a free ride on Nokia's innovation since it shipped the first iPhone in 2007".

We will keep you posted.