* OPEC pumps 33.39 million bpd in Sept, highest in at least 8 yrs
* U.S. crude falls back below $50 on report of rising crude stocks
By Henning Gloystein
SINGAPORE, Oct 13 (Reuters) - Oil prices fell early on Thursday after OPEC said that its production had risen to its highest level in at least eight years and following reports of an increase in U.S. crude stockpiles.
International Brent crude oil futures were trading at $51.52 per barrel at 0016 GMT, down 29 cents, or 0.6 percent, from their previous close.
U.S. West Texas Intermediate (WTI) crude futures were down 34 cents, or 0.7 percent, at $49.84 per barrel.
Traders said oil markets had come under pressure after Organization of the Petroleum Exporting Countries (OPEC) reported a rise in production, despite the producer cartel having plans, potentially with non-OPEC producer Russia, to cut output in a bid to rein in a global supply overhang.
"Crude responded predictably, with both Brent and WTI falling," said Jeffrey Halley, senior market analyst at brokerage OANDA in Singapore.
OPEC on Wednesday reported its oil production rose in September to the highest in at least eight years and raised its forecast for 2017 non-OPEC supply growth, pointing to a larger surplus next year despite the group's deal to cut output.
The producer cartel pumped 33.39 million barrels per day (bpd) last month, according to figures OPEC collects from secondary sources, up 220,000 bpd from August.
"In the absence of any OPEC-Russia headlines to give crude its daily adrenaline shot, the market looks nervously to the EIA Crude Inventory figures due in the US this evening," Halley added.
The U.S. Energy Information Administration (EIA) is due to publish official storage inventory data later on Thursday.
The American Petroleum Institute, a trade group, reported on Wednesday that U.S. crude inventories rose by 2.7 million barrels to 470.9 million barrels in the week to Oct. 7. This would be the first rise in oil stocks following five straight weeks of declines.
Reporting by Henning Gloystein; Editing by Richard Pullin