The music industry is dominated by a big artists and big firms

The new company, Sony BMG, became one of the music industry's biggest players, and the merger was opposed by a number of independent record labels.

Last year, a top European court upheld a complaint by the record labels that the merger needed more scrutiny.

The Commission said that its probe would run until 2 July.

Following the deal, Sony BMG controlled artists such as Elvis Presley, Bruce Springsteen, Rod Stewart and Christina Aguilera.

Extensive investigation

When the merger was announced, Impala, which represents more than 2,000 European music companies, said that too much of the market would be concentrated in the hands of a few large companies.

They warned that the deal would push up CD prices and reduce consumer choice.

At the time, the Commission said that these fears were unfounded.

Sony BMG is the world's second-largest music firm, and with rivals Universal Music, Warner Music and EMI it controls about 80% of the music market.

In a statement, the Commission said that it had previously looked at "whether the merger would create or strengthen a collective dominant position among the major music recording companies".

"This will also be an important element of the current extensive market investigation," it added.