Oil prices have risen 3% today, hitting the highest since early July 2015, as Saudi Arabia's crown prince cemented his power over the weekend with an anti-corruption crackdown, while the US rig count fell and markets continue to tighten.

Brent crude futures were trading $1.86 or 3% higher at $62.46 a barrel by 5pm Irish time.

US West Texas Intermediate (WTI) crude rose $1.49 or 2.7% to $57.13 a barrel.

Both benchmarks are at their highest since early July 2015.

Saudi Crown Prince Mohammed bin Salman tightened his grip with the arrest of royals, ministers and investors, including prominent billionaire Alwaleed bin Talal and the powerful head of the National Guard, Prince Miteb bin Abdullah. 

Analysts for now do not see Saudi Arabia, the world's largest oil exporter, changing its policy of boosting crude prices.

Prince Mohammed's reforms include a plan to list parts of state-owned oil company Saudi Aramco next year, and a higher oil price is seen as beneficial for its market capitalisation. 

Saudi Energy Minister Khalid al-Falih said that while there is "satisfaction" with a production-cutting deal between the Organisation of the Petroleum Exporting Countries and other producers led by Russia, the "job is not done yet". 

OPEC is expected to extend a cut of around 1.8 million barrels per day into the whole of 2018. 

Also boosting oil prices, US energy companies cut eight oil rigs last week, to 729, in the biggest reduction since May 2016. 

But while supplies are tightening, analysts say demand remains strong. 

"Synchronous global economic growth and new supply disruptions are creating the most constructive oil price environment since 2014," Barclays bank said.

The bank raised its forecast for the average Brent price in the fourth quarter of this year by $6 to $60 a barrel, and its full-year 2018 forecast by $3 to $55 a barrel.