Brent crude futures fell to just above $91 a barrel on Wednesday, holding to a months-long tumble in prices as lower economic growth forecasts raised new concerns about global oil demand amid rising US inventory levels.

The International Monetary Fund on Tuesday cut its global economic growth forecasts for the third time this year, warning of weaker growth in core eurozone countries, Japan and big emerging markets like Brazil.

While the IMF kept its growth outlook for China, the world's second-biggest oil consumer, unchanged at 7.4 percent for this year, it saw a risk of a hard landing in the medium term due to concerns over excess industrial capacity and credit.

"Growth concerns are on traders' minds, coupled with the glut in supply. The market is caught on a vortex of high supply and weak demand," said Ben Le Brun, market analyst at Sydney's OptionsXpress.

Brent for November delivery fell $1 to $91.11 by 0354 GMT after hit $91.03 earlier in the session, its lowest point since June 2012.

Oil prices have trended lower on oversupply and weak demand since mid-June, when Brent hit a nine-month high of $115.71.

West Texas Intermediate for November delivery dropped 93 cents to $87.92 a barrel after falling to $87.77 earlier in the session, its lowest since April 2013. – Reuters