Oil prices tumbled Tuesday as part of a selloff in commodities amid worries that a slowing global economy will dent demand for petroleum products.
The US oil futures benchmark, West Texas Intermediate for delivery in August, finished below US$100 a barrel for the first time in around two months, falling 8.2% to US$99.50 a barrel.
Brent oil futures for delivery in September plunged 9.5% to US$102.77 a barrel.
The sell-off came on a difficult day for global equities as well, with fears over inflation and tightening monetary supply battering bourses in Europe.
US stocks also spent much of the day in the red, but the Nasdaq later pushed into positive territory.
"Fears about the health of the world economy are circulating and that is why we are seeing major declines in stocks, energies, and industrial metals," said market analyst David Madden at Equiti Capital.
"There are increasing worries the elevated energy prices will chip away at demand, hence the fall in the oil contracts, said Madden.