The investigation into Intel's business practices has extended to South Korea, with the Korean Fair Trade Commission requesting documents from the chip giant over its rebate and marketing programs. The same programs are already under scrutiny in the US and Japan.

Intel said it was complying with a June request from South Korea's market watchdog to hand over materials related to Intel's discussions with South Korean PC manufacturers.

Intel rival AMD filed an anti-trust lawsuit against Intel in the US in June claiming that Intel is improperly using its marketing budget to exclude AMD's chips from PC and servers. Specifically, AMD accused Intel of cajoling vendors into using mostly Intel processors through the selective distribution of marketing funds to Intel-friendly vendors and threats of retaliation for purchasing AMD's chips.

That lawsuit built on an investigation by Japan's Fair Trade Commission that found Intel allocated marketing funds to Japanese PC vendors such as Sony and Fujitsu only if they agreed to purchase fewer processors from AMD. Intel did not deny the actual charges and agreed to end certain business practices, but disagreed with the negative characterization of those practices by the Japanese investigators and denied any wrongdoing.

Intel's marketing programs are also being looked at by the European Commission, which raided the offices of Intel and PC vendors in Europe last month as part of a "competition investigation", the Commission said at the time.