The US Justice Department has said it is investigating whether the world's leading semiconductor firms have been fixing prices in the memory chip market.

The allegations of cartel-like behaviour concern Dram chips, the most common type of memory chips used in personal computers around the world.

Under investigation

Micron Hynix Samsung Infineon Elipda Winbond

Prices in the Dram market, while notoriously volatile, have seen especially sharp swings in prices over the past months.

Analysts said the case might have resulted from complaints from angry computer makers who have suffered from price increases.

The firms under investigation include Korea's Samsung and Hynix, Germany's Infineon, US firm Micron, Japan's Elipda and Taiwan's Winbond.

Less power

News of the probe sent the share prices of companies concerned tumbling lower, with Micron losing 15% of its value during Wall Street trading on Wednesday.

"The investigation will weaken chipmakers' bargaining power over computer makers," said Samsung securities in a research note.

The chip makers have faced particularly hard times during the global economic slowdown and hi-tech turmoil.

And prices for memory chips have, at times, fallen below the cost of production, forcing widespread job cuts and factory closures.

The semiconductor firms took hope in a brief spike in the market earlier this year, when prices rose to a high of $4.8 from below $1 at the end of last year.

But the sudden spike also aroused suspicion.

Michael Dell, chairman and chief executive of Dell Computers, has already commented publicly that chip makers may be acting like a cartel.