Oil prices were near a three-year high above $ 70 a barrel on Monday amid signs that OPEC-led production cuts and Russia were cutting supplies, but some analysts warned of risks from rising US production.
In the latest trading, global benchmark crude rose 29 cents to $ 70.16 a barrel by 1937 GMT, after rising to $ 70.37 a barrel earlier in the session.
West Texas Intermediate crude futures rose 51 cents to $ 64.81 a barrel.
Both crude reached last week to unprecedented levels since December 2014, but trading was weak due to holiday in the US.
Oil prices have been heavily supported by a cut-off agreement between the Organization of Petroleum Exporting Countries (OPEC), Russia and some other producers.
Bank of America Merrill Lynch on Monday raised its estimate for Brent crude in 2018 to $ 64 a barrel from $ 56, expecting a 430,000 bpd deficit in oil production compared to demand this year.
“Producers in and outside OPEC are still committed to production cuts, while global demand continues to rise,” said Andrew Lippo, president of Lipo Oil Associates in Houston.
But some analysts have warned that oil gains of 13 percent since the start of the year could be eroded by global refinery maintenance and North American production.
US energy companies added 10 oil excavators in the week ending Jan. 12, bringing the total number of drilling platforms to 752, Baker Hughes Energy Services said on Friday.
This is the largest increase since June 2017.
In Canada, energy companies increased the number of oil drilling platforms almost twice last week to 185, the highest in 10 months.