US home entertainment chain, Blockbuster, is to expand DVD (Digital Video Discs) collections in its stores at the expense of its video cassette libraries.

The move reflects the growing popularity of the new format which has been encouraged by the rapidly falling price of DVD players.

About a quarter of the VHS cassettes in Blockbusters' 7,800 stores around the world will make way for DVD's.

Long-term, the move should be more profitable for Blockbuster, but the $450m cost of the changeover has concerned some investors.

Mass appeal

Sales of DVD players in the US are expected to reach 14 million this year.

About 18 million players have been sold in the last five years, according to research by the NDP Group.

Tom Edwards of NPD Group says it may only take 10 years for DVD to reach 90% of the population compared to the 25 years it took VCR's to achieve the same level of interest.

Steven Gaydos, executive editor of Variety International, told the BBC's World Business Report that the introduction of the DVD has brought many changes in the entertainment industry.

Home entertainment has now become a bigger market than the theatrical release of a film, he said.

"In a way the theatrical release of a picture is becoming a kind of loss leader, it is becoming the teaser, the promotional campaign that drives these huge numbers of DVD's now."

The image quality and extra features offered by DVD's, as well as their simplicity of use, appeal to consumers.

"With the DVD and the familiarity of the CD's it was inevitable that it would turn over very quickly," said Mr Gaydos.