By Karen Freifeld and Alexandra Alper

WASHINGTON (Reuters) -The United States is drawing up a list of advanced Chinese chipmaking factories barred from receiving key tools, three people familiar with matter said on Thursday, to make it easier for companies to stem technology flows into China.

The list could be released in the next couple of months, one of the people said.

The commerce department in 2022 barred U.S. companies from shipping equipment to Chinese factories producing advanced chips, as the U.S. seeks to severely limit Beijing's technological advances over national security concerns.

But companies say it is difficult to pinpoint which factories in China produce advanced chips and have long urged the commerce department to publish a list.

The effort shows the United States is taking pains to strengthen its existing chips restrictions on China by making it easier for U.S. firms to comply with restrictions.

The commerce department declined to comment.

A spokesperson for the Chinese Embassy in Washington said the U.S. should "stop overstretching the concept of national security and abusing the state power to suppress Chinese companies."

U.S. officials addressed requests from companies for a list at an annual export controls conference in Washington this week.

"People are like: 'Please, just tell us which are these advanced [factories] that you really care about,'" said one official, who spoke on a panel.

"It’s probably not going to be an exhaustive listing, if we can do that. But the more that we can help identify what are these facilities that we have a concern with, hopefully that’s going to help," the official added.