Oil prices closed modestly lower on Monday, retreating from the sharp rally of the previous session, on the impact of a strong dollar and worries of stubbornly high supplies as OPEC prepared to meet this week to stick to production targets.
The Organization of the Petroleum Exporting Countries pumped at a two-and-a-half year high of 31.22 million barrels of oil per day (bpd) in May, a Reuters monthly survey showed.
The boost from OPEC puts output further above its target of 30 million bpd, underlining the focus of top exporter Saudi Arabia and other key members on market share.
The group meets on Friday and is expected to maintain its current production policy, keeping the world oil market amply supplied for the foreseeable future.
"OPEC continues to produce well above target, and also well above demand for its oil," said Carsten Fritsch, senior oil analyst at Commerzbank in Frankfurt.