The lack of any immediate action by the world’s largest exporters to follow through on a proposal to freeze production at January’s levels also continued to undermine the market.
In a sign of the excess supply, U.S. crude stockpiles rose 3.5 million barrels last week to an all-time peak above 507 million barrels, data from the Department of Energy showed on Wednesday.
A slowing global economy also risks hurting demand for oil and keeping prices very low.
Citi cut its forecast for global economic growth this year to just 2.5 percent, from a previous forecast of 2.7 percent.
“Global growth prospects are worsening further, with deterioration across advanced economies alongside previous weakness in emerging markets,” Citi economists said in a research note.
A boost for oil prices after Saudi Arabia, Russia, Venezuela and Qatar last week proposed to keep their output unchanged from January, provided other major OPEC and non-OPEC producers joined them, has since faded.