Oil prices settled 1% lower on Tuesday as investors worried about a supply glut after Iranian and U.S. delegations made progress in their talks and on expectations that OPEC+ will decide to increase output at a meeting this week.

Oil prices remained mostly flat on Monday as investors weighed geopolitical tensions and upcoming economic data from China, the worlds second-largest oil consumer. Brent crude dipped 5 cents to $65.36 per barrel,

Oil prices slipped as traders assessed the implications of diplomatic overtures on multiple fronts –including Russia-Ukraine peace talks and US-Iran nuclear negotiations – while a cautious outlook for China’s economy further dampened sentiment.