While the company has declined to comment on the matter, the sources said the low price at the iTunes Music Store was likely a mistake.

The bargain was available last Thursday from the early morning to late afternoon, when it was possible to download Toshiba EMI Ltd. albums at 50 yen each.

Dozens of albums, including those by rock group RC Succession and singer Saori Yuki, sold at the price.

"This must be due to confusion on the sales side because of the unexpected popularity of the service," said music journalist Daisuke Tsuda.

Apple started its Japanese version of the hugely popular iTunes download service Aug. 4, offering about 1 million songs from 15 record companies. About 1 million tunes were sold online in the first four days of operation, the company has reported.

Prices for a single song downloaded using a special program range from 150 yen to 200 yen. An entire album starts at 1,500 yen.

People who downloaded the albums last Thursday received sales confirmations via e-mail from Apple with the 50-yen price, the sources said. Credit card billing statements for the purchases will also list the 50-yen price.

"We have heard talk about it (the low price), but our company is involved (only) in selling wholesale. The actual prices are up to the Web site," a Toshiba EMI representative said.

Although Apple apparently fixed the mistake, the damages could have been devastating.

"Unlike for ordinary merchandise sales, a music download service never runs out of stock," journalist Tsuda said. "If the recent incident was indeed a mistake, potential losses for the company selling the songs could expand without limit."