LOS ANGELES (Reuters) - Warner Bros on Monday became the first studio to open its film vault to “made-to-order” DVDs, as it sought new revenues in a slumping DVD market by making it possible for fans to buy decades-old films.

Warner Bros, owned by Time Warner Inc, made an initial batch of 150 titles available for purchase online at www.WarnerArchive.com , including 1943 comedy-romance "Mr. Lucky" starring Cary Grant and the 1962 release "All Fall Down" with Warren Beatty and Eva Marie Saint.

Sales are not expected to approach those of new releases on DVD, but the service gives Warner Bros another way to make money from a film archive it already exploits by selling titles for broadcast in the United States and internationally.

The on-demand service allows Warner Bros. to avoid the risk of manufacturing too many copies of old or obscure titles and shipping them to retailers because customers directly order only the titles they want to buy.

“This way you’ve completely eliminated the risk of not selling them. You’re not going to make them until they’re sold,” said Tom Adams, president and senior analyst with Adams Media Research.

Warner Bros. said that each month it will make about 20 films and television programs from its archive available for purchase through this DVD-on-demand program.

The new Warner Bros. initiative comes as the movie industry faces declining DVD sales. Last year, amid the ongoing recession DVD sales fell by 7 percent to $21.6 billion, the Digital Entertainment Group said.

Studios are mainly looking to the emerging Blu-ray disc market to counter declining DVD sales, Adams said.

Last year, sales of Blu-ray discs quadrupled to nearly $750 million, the Digital Entertainment Group said.

But with the new DVD-on-demand service, Warner Bros can supplement its sales by appealing to collectors and fans.

The Warner Bros film archive has 6,800 titles. Since it entered the DVD market in 1997, the studio has released only around 1,200 of those titles from the vault. By comparison, the company expects by the end of the year to have more than 300 titles available via the DVD-on-demand service.

“I think ultimately the odds are very good that every film ever made will be available on this kind of basis, because why not?” Adams said.

Warner Bros. is charging customers $19.95 per title, plus shipping, for the new service. Titles also can be downloaded directly to a customer’s computer.