08:40 AM EDT, 10/28/2025 (MT Newswires) -- Oil prices weakened for a third day early Tuesday as the market's focus returns to rising inventories and an over-supplied market.

West Texas Intermediate crude oil for December delivery was last seen down US$0.78 to $60.53 per barrel, while December Brent oil was down $1.00 to $64.62.

Oil rose to a two-week high last week after the Trump Administration threatened to impose fresh sanctions on Russian oil producers to limit Russia's ability to fund its war on Ukraine. However the gains failed to hold amid doubts over U.S. President's willingness to enforce measures against Russia. Instead, attention returned to rising inventories amid increasing supply from OPEC+ and its competitors ahead of a second 137,000 barrel per day monthly quota hike coming Saturday from the cartel.

"The supply side that remains in focus, as doubts about efficiently enforcing Russian oil sanctions resurface and, as reported by Reuters, eight OPEC+ members are contemplating yet another slight output increase during their monthly meeting at the end of the week," PVM Oil Associates noted.

Both the Energy Information Administration and the International Energy Agency have warned inventories are likely to climb on higher supply, with the IEA warning earlier this month that September supply was 5.6-million barrels per day above year-prior levels, even as demand growth remained weak, up only 0.7-million bpd, a level it expects to continue into 2026.