United States crude oil prices have fallen sharply to their lowest since 1999 due to plunging demand amid the coronavirus pandemic.

In the morning of Asian trading, US crude oil prices plummeted more than 20 per cent to below $US15 a barrel for the first time in 21 years.

This was despite a deal earlier this month by the OPEC+ countries – an expanded format of the Organisation of Petroleum Exporting Countries (OPEC) – to cut production by 9.7 million barrels per day for May and June.