Hong Kong and mainland shares fell while US stock futures rose sharply hours before the opening of markets on Wednesday as Republican Donald Trump claimed victory in the American presidential election.

The greenback surged and bitcoin hit a record high, with traders ramping up bets on fresh tax cuts, tariffs and rising inflation.

Here in Hong Kong, the Hang Seng Index snapped a three-day winning streak, finishing 468 points or 2.2 percent lower at 20,538.

Mainland stocks also closed lower, with the Shanghai Composite Index down 0.09 percent to 3,383 and the Shenzhen Component Index losing 0.35 percent at 10,968.

Analysts said the prospect of another Trump presidency and Republican control of US Congress risked heightened tensions between Beijing and Washington over trade and technology.

"Right now, the markets are focusing narrowly on the prospect of tariffs because it is the easiest lever to pull directly under a presidential executive order, but we’ve seen between 2016-20 other levers that can be pulled to contain China," said Rong Ren Goh, a portfolio manager in the fixed income team at Eastspring Investments.

"Although both candidates are probably hawkish toward China, Trump is still less predictable in terms of policy, so the prospect of a Trump win could still drag sentiment a bit," said Kenny Ng, strategist at China Everbright Securities International.

Stock futures were up 2.2 percent for the Dow, 2 percent for the broad-based S&P 500 and 1.7 percent for the tech-heavy Nasdaq.

Meanwhile, the US dollar jumped 1.5 percent to 154.38 yen, its highest since July, while it was also up more than 1 percent against the euro and more than 3 percent against the Mexican peso.

The offshore yuan fell more than 1 percent versus the greenback, to its weakest since mid-August.

Bitcoin sprung US$6,000 higher to a record US$75,371.69, topping its previous peak of US$73,797.98 in March.

Trump has pledged to make the United States the "bitcoin and cryptocurrency capital of the world" and to put tech billionaire Elon Musk in charge of a wide-ranging audit of governmental waste.

"The price of bitcoin has closely followed Trump's position in the polls and on betting markets," Russ Mould, an analyst at AJ Bell, said ahead of Tuesday's US election.

Investors are "potentially taking the view that a Republican victory would lead to a surge in demand for the digital currency", he added.

Peter Esho, economist and founder at Esho Capital, said: "The markets are scrambling to figure out what happens next, but for the time being, the market is pricing in a higher growth and higher inflation outlook." (Agencies)