By Wen-Yee Lee and Ben Blanchard

TAIPEI, April 30 (Reuters) - Taiwan's ASE Technology Holding Co. 3711.TW has yet to decide how it will support a plan by Nvidia to build artificial intelligence servers worth as much as $500 billion in the U.S. over the next four years, it said on Wednesday.

The company, the world's largest chip packaging and testing provider, is still evaluating an invitation from a customer to invest in the U.S. and has yet to decide on the investment size or timing, its Chief Financial Officer Joseph Tung told an earnings call.

He did not name the customer but the company later confirmed to Reuters that he was talking about a plan announced by AI chip giant Nvidia made public earlier this month to expand production in the U.S., with the help of partners including ASE subsidiary Siliconware Precision Industries.

Analysts have questioned whether the sum of $500 billion is realistic, given difficulties suppliers may have in moving production.

Nvidia did not immediately respond to a request for comment.

The customer had invited ASE to "evaluate the possibility of having some operations to support their business in the U.S," Tung said.

"Currently we are engaging in discussion and are evaluating opportunities with interest. There are no further details so far in terms of the actual investment size or the timing of it. But any decision that we will eventually make will be made with economic viability."

When asked by analysts about what kind of product would be considered, Tung he said it would be an extension of what the company offers in Taiwan.

Siliconware Precision Industries, which carries out chip packaging for Nvidia, has no manufacturing presence in the U.S. Another ASE subsidiary, ISE Labs, has two testing factories in California.

(Reporting by Wen-Yee Lee and Ben Blanchard; editing by Barbara Lewis)

((wen-yee.lee@thomsonreuters.com))