Around 1145 GMT, US benchmark West Texas Intermediate (WTI) for delivery in May added $1.39 to $38.65 a barrel.
Brent North Sea crude for June delivery won $1.33 to $40.76 a barrel compared with Friday's close.
The oil market had rebounded last week on supportive US figures, with both contracts winning eight percent or more in value.
Data showing US stockpiles and output had seen a surprise fall provided some much needed impetus, with a fall in the number of rigs drilling also providing strong support.
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However, the key focus is now on the April 17 meeting in Doha, where most of the world's top producers led by Russia and Saudi Arabia will discuss global oversupply.
A chronic worldwide supply glut sent oil prices collapsing by three quarters between August 2014 and February this year.
"There are clearly increased hopes again that the meeting of oil producers in Doha next Sunday will produce a substantial result after all," said Commerzbank analyst Cartsten Fritsch in a research note to clients.
"We are sceptical about this... There is thus a risk of a price correction if the market is disappointed by the outcome of the meeting."
While there is a growing expectation the Doha meeting will see signatories agree to a production freeze at January 2016 levels, analysts remain uncertain of the long-term impact of such a deal.