RealNetworks CEO Rob Glaser has appealed to Apple to support other proprietary music formats with the iPod.

According to Cnet Glaser told a PC Forum panel: "Apple is creating problems for itself by using a file format that forces consumers to buy music from Apple's own iTunes site.

"Apple's market share will go down if it continues to do this. The only way to presently put songs on an iPod is to (buy) them from iTunes."

Glaser suggested that HP may be able to persuade Apple to change its practice – HP has partnered with Apple and will sell an HP-branded iPod and include iTunes on its PCs.

Glaser predicted that customers will say: "I bought an iPod and can only shop at one store. What is this? The Soviet Union?"