AMD has expanded its legal action against Intel by filing an anti-trust lawsuit in Japan, to go with the one it brought against the chip giant in the US earlier this week.

It is seeking $50 million in damages arising for what it claims are violations of Japan's Anti-monopoly Act, plus "millions of dollars in damages" for "various anti-competitive acts" by Intel.

The lawsuits are related to a March ruling by the Japan Fair Trade Commission (JFTC), which found that Intel had abused its monopoly power in the Japanese micro-processor market, substantially restraining competition. Intel disagreed with the findings, but pledged to refrain from several types of business practices.

Meanwhile, Intel has angrily dimissed AMD allegations against it.

"We unequivocally disagree with AMD's claims," said Intel president and CEO, Paul Otellini. "Intel has always respected the laws of the countries in which we operate,"he continued. "We compete aggressively and fairly. This will not change."

The company said it has faced similar anti-trust issues in the past and predicted it will be able to resolve the AMD lawsuit "favorably".

Right or wrong, Intel's dominance of the computer processor business makes it an easy target for anti-trust suits. In the first quarter of 2005, Intel shipped 81.7 percent of the world's desktop, server and notebook processors based on the x86 instruction set used by both AMD and Intel to run their processors.

AMD's 48-page complaint alleges that Intel used illegal subsidies to win sales, and in some cases threatened computer makers with "severe consequences" for carrying AMD products.

In order to win its case, AMD needs to demonstrate that Intel is in possession of monopoly power, and that the company is guilty of abusing that power to maintain its dominance and harm consumers.