Brent crude, the benchmark oil price, has risen 1.17% to $82.15 a barrel.
Meanwhile Mohammad Barkindo, secretary general of Opec, the cartel of Middle East and African oil producing nations, has just said that it is important for the group to cooperate with non-Opec nations "so that we do not fall from one crisis to another".
Only way is up for petrol prices
BBC Radio 4
Rising oil prices mean that eventually it will cost more to fill up a car.
We're going one way and that's up," Aneeka Gupta, research analyst at Wisdom Tree tells the Today programme.
But she says that Saudi Arabia - the largest member of Opec - would not want oil prices to go too high.
"Although they require a higher oil price to fund their fiscal spending and help their economy, they don't want a price too high. What Opec really wants, what Saudi really wants is a stable oil price between $70 and $85 a barrel."
In terms of where next for prices, Ms Gupta says: "I believe the price will eventually trade within a range. I think the maximum it should trade is $85 a barrel. I believe we would see intervention from the Opec members."
Outages force crude higher
BBC Radio 4
Aneeka Gupta, research analyst at Wisdom Tree, also points out that a sharp drop in Venezuela's oil output - down from three billion barrels a year to one billion barrels a year - has contributed to rising oil prices.
"That was a very very big contributor to the increase in Brent prices over the course of this year. We've also seen outages from Libya so these two have been considerable factors helping the Brent price to rise."
Key meeting supports oil price rise
BBC Radio 4
Brent crude - the benchmark oil price - is now trading at its highest for four years and could reach $90 a barrel by Christmas, according to some analysts.
Aneeka Gupta, research analyst at Wisdom Tree, tells BBC Radio 4's Today programme that a lot of the rise is because of the meeting between Opec and non-Opec members at the weekend.
"They have refused to raise production," she says. "Earlier in June this year they had set forward a proposal of raising production by one million barrels per day.
"They said they would look into this as time progressed and this Sunday was essentially that key point when they could decide whether it was the right time to increase production given that we are seeing sanctions on Iran come into play and we're seeing exports from Iran start to decline."
Oil maintains gains
Oil held onto gains overnight with Brent crude up 0.30% at $81.44 a barrel while West Texas Intermediate rose 0.22% to $72.24.
Opec and non-Opec members, including Russia, decided not to increase oil output at a meeting at the weekend despite calls from US President Donald Trump to lower prices.
Also, US sanctions against Iran - one of Opec's largest producers, are due to come into force in November.
Oil price has hit a four year high today but some analysts are predicting they could continue to rise.
"Fears of Iranian production being hit by the imminent US sanctions have caused some to predict a strong move higher ahead for crude, and the unwillingness of OPEC and other key producers to attempt to offset this increases the risks of a supply shock further, which could feasibly drive prices as high as $90 or even $100 a barrel by year-end."
Oil price rises above $80
Brent crude has risen to $80.50 a barrel - the highest since November 2014.
Prices have risen after Opec, at a meeting with the likes of Russia in Algiers ruled out any increase in output.
Last week, US President Donald Trump told Opec to lower prices. But Saudi Energy Minister Khalid
al-Falih said: "I do not influence prices."
Oil prices rise after OPEC snubs Trump request
Last week, US President Donald Trump ordered OPEC to lower oil prices.
This week, the cartel of oil producing nations completely ignored him and at a meeting in Algiers with Russia, decided not to increase oil output and sent crude prices higher.