Donald Trump's withdrawal from the Iran nuclear deal is set to put extra pressure on our Government's bottom line.

The re-introduction of US sanctions is contributing to the rise in Brent crude prices.

Plummeting production from Venezuela and growing demand from emerging economies is also contributing to the price rise.

JMIS analyst Jason Watson told Mike Hosking the rise wasn't factored into last week's budget.

"This is going to pressure on the Government's growth forecast, but more important the tax take the Government needs to implement their spending plan."

Watson says petrol prices could rise much faster than people expect.

"The analysts are actually picking the doors going to go over $100, which could easily see petrol in New Zealand at $2.50, especially with the additional tax we're talking about."

LISTEN TO JASON WATSON TALK WITH MIKE HOSKING ABOVE