The US Federal Trade Commission is launching an anti-trust investigation into Intel, the chip manufacturing giant.

Intel said the FTC served a subpoena on the company last week, and it pledged to co-operate with the regulator to provide any required information, as it has since 2006, when the FTC began an informal inquiry.

"The company believes its business practices are well within US law," Intel said in its statement. "The evidence that this industry is fiercely competitive and working is compelling."

Prices for microprocessors declined by more than 42 percent between 2000 and 2007, Intel noted.

An FTC spokesman said he could confirm the investigation but couldn't give more details.

The FTC investigation comes a day after the Korea Fair Trade Commission fined Intel a reported 26 billion won (£13 million) for abusing its dominant position in the microprocessor market. Intel offered rebates to South Korean computer makers in a way that unfairly harmed its rival Advanced Micro Devices, the Korean agency said.

In January, New York state Attorney General Andrew Cuomo launched an antitrust investigation of Intel.

Japan and the European Commission have also investigated Intel, and AMD has a pending civil lawsuit against the company.

The Fair Trade Commission of Japan (JFTC) in 2005 recommended that Intel end its practice of offering funds to PC makers in exchange for a commitment not to use processors from its competitors. Intel accepted those recommendations, which came after a lengthy JFTC investigation, saying at the time it wanted to avoid a protracted legal battle.

The Computer & Communications Industry Association (CCIA), a trade group with AMD as a member, praised the FTC for opening the investigation.

The FTC investigation is "long due," said Ed Black, CCIA's president and CEO. After investigations by South Korea, Japan, and the European Commission, it was time for the US government to act, Black said.

Intel has a strong set of products, Black added. "They should not have to abuse their power and break the law in order to be successful," he added.