Oil prices fell on Thursday, extending losses from the previous session, as signals of higher supply from the United States met worries about lackluster energy demand from China.

Brent futures were down 48 cents at $80.70 a barrel at 0630 GMT. US West Texas Intermediate crude (WTI) shed 53 cents to $76.13 a barrel.

Both benchmarks fell more than 1.5 percent in the prior session.

WTI's front-month contract also traded below the price for the second month, a structure known as contango, suggesting that investors expect prices to increase. The front month's discount to the second month traded at minus 17 cents on Thursday.

"Concerns over a record-high US production rate put fresh pressure on oil prices, adding to an already worrisome demand outlook," said Tina Teng, a markets analyst at CMC Markets in Auckland.

US crude stocks rose by 3.6 million barrels last week to 421.9 million barrels, according to the US Energy Information Administration (EIA), far exceeding analysts' expectations in a Reuters poll for a 1.8 million-barrel rise.

US crude production held steady at a record 13.2 million barrels per day (bpd).

In Asia, China's oil refinery throughput eased in October from the previous month's highs as industrial fuel demand weakened and refining margins narrowed. Still, its economic activity perked up in October as industrial output increased at a faster pace and retail sales growth beat expectations.

Data released on Thursday morning underscored concerns around China's property sector, showing that new home prices fell for a fourth consecutive month in October, with property sales by floor area down 20.33 percent year-on-year.

Technical factors were also restraining any upward movement in prices, said Jun Rong Yeap, a market strategist at IG in Singapore.

"Given that the tighter oil supply-demand dynamics have been less prominent from months ago, there has been some unwinding in previous bullish positioning ever since, with prices falling back below their 200-day moving average as a sign of sellers in control," Yeap said.