Oil prices extended gains on Monday morning, propped up by a weaker US dollar and tight supplies, Reuters reported.

Brent crude futures for September settlement rose $2.54, or 2.5%, to $103.70 a barrel, after a 2.1% gain on Friday.

And the US West Texas Intermediate (WTI) crude futures for August delivery gained $2.31, or 2.4%, to $99.90 a barrel, after climbing 1.9% in the previous session.