Graphics firm Nvidia has stepped up its legal battle with Intel, filing a countersuit in the cross-licensing spat with the chipmaker.

Intel first filed suit against Nvidia last month over the cross-licensing agreement that the two companies signed in 2004. The case centred around Intel's claim that its latest lines of processors contain elements such as onboard memory controllers, and should not therefore qualify under the deal.

Nvidia countered with a harshly worded statement claiming that Intel had acted out of spite for the growing power of the graphics processing units that Nvidia makes.

Nvidia has now stepped up its resistance by filing a countersuit seeking to end Intel's access to its patent portfolio.

"We must defend ourselves and the rights we negotiated when we provided Intel with access to our valuable patents," said Nvidia president and chief executive Jen-Hsun Huang.

"Intel's actions are intended to block us from making use of the very licence rights that they agreed to provide."