Global oil price benchmark Brent crude fell 7.8 per cent to $30.32 per barrel in turbulent trading today today - hovering on the brink of the psychologically significant $30 mark.
Meanwhile, US oil price benchmark WTI crude fell 5.9 per cent, crashing to $27.94 per barrel.
Brent crude has traded above $30 since the end of January - but it was pushed lower today after a report from the International Energy Agency suggested any optimism was misplaced, warning of a "false dawn".
"Perhaps some of the more fevered forecasts of oil prices falling as low as $10 per barrel are extreme and better days do lie ahead for oil prices," it said.
"However, before the victory over the bearish forces is declared we should look at the main factory driving this optimism."
Elsewhere, an annual review of the UK oilfield services sector suggested tumbling prices had plunged the sector into "unknown territory".
"The cyclical nature of the oil price is something the industry has experienced before," said Derek Leith, head of oil and gas tax at EY.
"But this time the effect is more brutal and the need for change is greater."