* Asia chip stocks extend Wall Street's selloff

* TSMC, Tokyo Electron, SK Hynix among biggest losers

* TSMC due to report earnings later on Thursday

SINGAPORE, July 18 (Reuters) - Chip stocks in Asia tumbled on Thursday, tracking a heavy selloff on Wall Street spurred by a news report that the United States was mulling tighter curbs on exports of advanced semiconductor technology to China.

Among the worst hit were shares of Taiwan Semiconductor Manufacturing Co (TSMC), the world's largest contract chipmaker, which has shed roughly T$2 trillion ($61.35 billion) in market value over two days.

TSMC, which reports earnings later on Thursday, has taken a double hit this week from reports of the U.S. curbs as well as remarks from U.S. Republican presidential nominee Donald Trump that Taiwan should pay America for its defence.

TSMC fell more than 3%, joining other technology behemoths such as South Korea's major chipmakers Samsung Electronics and SK Hynix, which were down 1.85% and 4.1%, respectively, and Japan's Tokyo Electron, which slumped more than 8%.

The Global X Asia Semiconductor ETF was down 2.7%, reducing gains for the year to 13.5%.

The Bloomberg News report published during Asian trading hours on Wednesday said President Joe Biden's administration was weighing a measure called the foreign direct product rule that allows the U.S. government to stop a product from being sold if it was made using American technology.

That would potentially mean restrictions on companies such as Tokyo Electron and Netherlands' ASML.

TSMC's American Depository Receipts slid 8% on Wednesday. In its first-quarter earnings report, TSMC said 69% of revenue was from customers based in North America and 9% came from China.

Washington's protectiveness towards the U.S. semiconductor manufacturing industry, which it views as strategically important for competing against China, has raised increasing concerns for investors.

"It seems macro and geopolitical factors played a bigger role than fundamentals," said Kang Jin-hyeok, an analyst at Shinhan Securities in Seoul.

Kang was referring to the strong recent earnings releases from Samsung and ASML, but noted the latter's heavy sales to China make it a target of the proposed U.S. curbs.

China accounted for about 49% of ASML's lithography system sales in the second quarter and represents about 20% of its order backlog.

ASML shares fell more than 10% on Wednesday, despite forecast-beating second-quarter earnings that showed a rise in artificial intelligence-linked bookings.

The Biden administration has moved aggressively to curb Chinese access to cutting-edge chip technology, including sweeping restrictions issued in October to limit exports of AI processors designed by firms including AI darling Nvidia .

The latest wrinkles in Sino-U.S. relations have sped up what appeared to be initial signs of investors' rotation from Big Tech stocks into smaller value ones, on the view that lower U.S. rates will benefit smaller companies.

"Positioning had become very extreme in the semi-conductor/AI space and the import curb comments catalysed a de-risking event," said Jon Withaar, who manages an Asia special situations hedge fund at Pictet Asset Management.

Tech stocks have outperformed this year on the back of the global AI boom, with the Nasdaq up 20%, while the S&P 500 has surged 17%.

But the selloff in Asia on Thursday left major bourses in the red, with Tokyo's Nikkei down 2%, while Taiwan stocks slid 2.3%.

South Korea's benchmark KOSPI index fell 1.34%. Hong Kong's Hang Seng tech index lost 1.5%. ($1 = 32.6010 Taiwan dollars)

(Reporting by Youn Ah Moon in Seoul, Jeanny Kao in Taipei and Ankur Banerjee in Singapore; Writing by Rae Wee; Editing by Vidya Ranganathan and Jamie Freed)