The IEA said: “While there has been some speculation that the high cost of unconventional oil production might set a new equilibrium for Brent prices in the $80 to $90 range, supply/demand balances suggest that the price rout has yet to run its course.”

Barring any new supply disruption, ‘downward price pressures could build further in the first half of 2015’, it said.

In Iran, the state-run Ebtekar daily newspaper said on November 8 that the regime’s budget deficit was $1.5 billion – but economists now believe the true figure is much higher.

The Tehran government had calculated its budget for 2014 based on oil priced at $100 per barrel and oil exports of around 300,000 barrels per day.

Hassan Rouhani’s vice-president Eshagh Jahangiri is now insisting the glut of oil on international markets is ‘politically-motivated’.

He said last week: “Some countries have increased their oil exports for political reasons, and these countries will face the reaction of the Muslim people.”