North Sea oil fears:

OIL prices fell by as much as a dollar a barrel after Iran and six world powers reached a nuclear accord that clears the way for Tehran to unleash its vast oil reserves on to the world markets.

Union leaders have previously warned that a historic deal on Iran’s nuclear programme could be disastrous for the oil industry in the North Sea.

The accord over Iran’s nuclear programme has heightened expectations of a wave of cheap oil flooding global markets after sanctions are lifted, with some experts warning of a plunge in prices.

Benchmark Brent crude prices by the end of trading were up 55 cents, or nearly one per cent, at $58.40 a barrel after having plumbed a low of $56.43.

Industry body Oil and Gas UK has estimated that around 20 per cent of UK production is uneconomic at a $50-per-barrel oil price.

The lifting of sanctions is expected to see a surge in Iran’s oil output.

The Scottish Government last month dramatically lowered its estimates for how much revenue will be generated from North Sea oil and gas - and gave their most pessimistic scenario as £2.4 billion between 2016/17 and 2019/20.

That prediction was based on an oil price of $70 per barrel – $12 a barrel less than the current price.

Iran is understood to have a glut of unsold oil ready to hit markets and is thought to have some 30 million barrels held in a fleet of tankers. However, Tehran is prepared to produce up to one million barrels a day.

Before implementation of sanctions imposed by the EU and US in the middle of 2012, Iran was exporting 2.5 million barrels.

Iran could increase its oil exports by up to 60 per cent within a year, according to a survey of 25 oil analysts.