Apple and four of the biggest record companies have until Wednesday to submit their written response to antitrust charges that they restricted online sales of music in Europe.

The deadline originally expired at the beginning of June, but was extended by two weeks at the request of Apple and three of the record companies, European Commission competition spokesman Jonathan Todd said today.

The Commission is still waiting for replies from these four companies. The one record company that didn't request an extension has already submitted its written response, Todd said.

The Commission has declined to name the record companies involved but they are assumed to be the four majors: Sony BMG Music Entertainment, Universal Music, Warner Music and EMI Group.

"We have every reason to believe that the remaining companies will reply by the new deadline," Todd said.

Downloads from Apple's iTunes website are priced differently in different countries in the Union but consumers are prevented from shopping around and have to make their purchases of music from the iTunes site in the country they are based.

The Commission said that in the single European market the distribution agreements between the record companies and Apple could amount to restrictive practices.

Apple claims it has always tried to operate a single pan-European iTunes store accessible by anyone from any member state but has been prevented from doing so by the record labels and publishers.