The US International Trade Commission (ITC) has launched a probe into Apple's iPod music player, following complaints by Creative Technology of intellectual patent infringement.

The move comes after a spate of tit-for-tat patent filings from both firms which has been going on for months.

Creative began its patent dispute with Apple in December 2005. The firm alleges that Apple has imported into the US and sold iPod products which infringe a patent covering the user interface in its Nomad and Zen portable digital media players.

The company has asked the ITC to issue a 'cease and desist' order against Apple to stop it selling, marketing or importing its iPod players into the US.

Creative was one of the first firms to sell a digital music player back in 2000, but has seen huge market share clawed away by Apple's iPod.

The ITC normally issues a ruling 12-15 months after an investigation begins. The case is to be passed to administrative law judge Paul Lukern, who will hold hearings and present an initial judgement as to whether or not any infringement has taken place.

Meanwhile Apple is doing some investigation of its own into a report featured in the Mail on Sunday newspaper claiming that staff in some of its iPod factories in China are working in 'slave' conditions.

In a statement the company said: "Apple is committed to ensuring that working conditions in our supply chain are safe, that workers are treated with dignity and that manufacturing processes are environmentally responsible."