Brent Drops Below $90; Worry Over Global Economy, Supply

In China, a Reuters poll forecast that soft domestic demand probably slowed imports, investment and retail sales to multi-month or multi-year lows in September.

Brent's front-month fell by $1.33 to settle at $90.05, its lowest settlement since June 2012. It continued to plunge in post-settlement trading, touching $89.14. Reuters charts showed potential support for Brent at a December 2010 low of $85.41.

Front-month WTI settled at $85.81, its lowest settlement since December 2012, and continued to fall in post-settlement trading to a low of $85.02.

Gasoline shed 4.3 cents to settle at $2.27 a gallon, its lowest since December 2010.

"You can draw as many technical support levels as you like on these markets from the charts, but none may really matter given the psychological stampede they are going through now," said Andy Lebow, vice president at Jefferies LLC in New York.

Sentiment was also bleak from data a day earlier that showed U.S. crude inventories having a 5-million-barrel build in the week to Oct. 3. Analysts polled by Reuters had expected a rise of just 1.5 million barrels.

Some analysts said the selloff may be overdone.