South Korea's Dong-A Ilbo quoted an anonymous diplomat as saying the U.S. would exempt South Korean chipmakers from requests to limit mainland China's access to chip-making equipment, allowing Samsung Electronics and SK Hynix to import U.S. equipment for their factories in mainland China.

The U.S. Commerce Department explained directly to the South Korean government that its export controls on equipment that can make chips more advanced than 14 nanometers will not affect South Korean chip makers in mainland China.

Bloomberg previously quoted Lam Research and KLA equipment manufacturers as pointing out that the United States is tightening restrictions on mainland China's access to chip manufacturing equipment from 10 nanometers to 14 nanometers.

In the past two weeks or so, all U.S. equipment makers have received letters from the Commerce Department asking them not to supply mainland China with equipment used in more advanced chipmaking with 14-nanometer chips, people familiar with the matter told Bloomberg. The Commerce Department has actually rejected many 14-nanometer licenses before, so the change has little financial impact on many companies, they said.

Lam Research executives said they had factored the impact of the U.S. request into their outlook for the September quarter, without elaborating.

KLA CEO Rick Wallace also confirmed that his company has also received relevant notifications from the US government, saying that there is no significant impact on KLA's business.