Oil markets
Pump jacks are seen at the Lukoil company owned Imilorskoye oil field, as the sun sets, outside the West Siberian city of Kogalym, Russia, January 25, 2016.Reuters

Oil prices tumbled on Wednesday as vote counting showed Republican Donald Trump doing better than expected in several crucial battleground states in the U.S. presidential election.

With traders glued to their screens, crude futures markets roared into action as counting advanced, with Trump holding narrow leads over Democrat Hillary Clinton in a series of key contests.

U.S. West Texas Intermediate (WTI) CLc1 crude futures fell to a session low of $43.07 per barrel, down more than 4 percent from their last close and their lowest since September, before inching back to $43.30 a barrel at 0333 GMT.

International Brent crude futures LCOc1 were down 3 percent at $44.68 a barrel.

"This is dejavu of the Brexit moment, very worrying," said Bob Takai, president at Sumitomo Corp Global Research in Tokyo, referring to Britain's surprise vote to leave the European Union in a referendum last June, which led to market turmoil.

The falls in oil came as prices for gold, a traditional safehaven for investors in times of uncertainty jumped, while the dollar fell sharply against a basket of other leading currencies.

"Traders are sort of watching other vehicles like U.S. dollar futures and gold," said Ric Spooner of CMC Markets in Sydney, Australia.

Trump won the key battleground state of Ohio and led Clinton in a series of other states that were too close to call, including Florida and North Carolina, in a surprisingly close race for the White House.

Elsewhere, a report by the American Petroleum Institute (API) showed crude inventory figures rising by 4.4 million barrel was also weighing on markets.

In Asia, physical oil analysts were digesting mixed data out of China on Tuesday, which showed a fall in crude imports and a rise in exports of refined products.

"Crude oil net imports fell to just 6.8 million barrels per day (bpd) in October, down from 8.1 million bpd the previous month. Although this is a very large drop, to the lowest monthly import level since January 2016, it is still up 8 percent year-on-year," Barclays said.

Barclays said that the monthly decline was likely a result of falling strategic stockpiling.

"Some (independent) 'teapot' refineries are also thought to have used up their crude oil import quotas for the year, and that may also be having a negative effect on crude oil import demand at the margin," the bank added.