Brent crude, the benchmark, rose 92 cents, or 1.0 percent, to $90.95 a barrel by 0051 GMT, following gaining 69 cents on Friday.
US West Texas Intermediate crude rose 99 cents, or 1.1 percent, to $87.81 a barrel, following rising 21 cents on Friday.
On Friday, the two benchmarks hit their highest level since October 2014.
The major producers in the Organization of the Petroleum Exporting Countries (OPEC) and its allies led by Russia in what is known as (OPEC +), are seeking to raise their production levels. The market was also affected by the attacks launched by the Yemeni Houthi movement on the United Arab Emirates.
Tensions between Russia and the West have pushed up oil prices. The row between Russia, the world’s second-largest oil producer, and the West over Ukraine has raised fears of a possible energy shortage in Europe.