Russian production hit a post-Soviet record in 2018, figures showed on Wednesday. Other data showed US output reached a record in October and Iraq boosted oil exports in December.
Brent crude was 33 cents lower at $53.47 a barrel at 1214 GMT. On December 26, it hit $49.93, the lowest since July 2017. US crude slipped 40 cents to $45.01.
"The omens are far from encouraging," said Stephen Brennock of PVM oil broker, citing rising non-OPEC supply and the likelihood of further increases in oil inventories.
Oversupply, faltering growth to weigh on oil prices in 2019
"The current bearish bias will, therefore, continue in the near term and it stands to reason that oil will struggle to break out from its current trough," he said.
However, WisdomTree Director Research Nitesh Shah saw the prospect of a rebound for Brent because of an OPEC-led supply cut that starts this month and moderating US supply growth.
"We believe we will see an upward correction," he said. "Recent weakness in prices should slow the growth of US shale production."
Oil prices fell in 2018 for the first year since 2015 after buyers fled the market in the fourth quarter over growing worries about excess supply and the economic slowdown.
Surging shale output has helped make the US the world's biggest oil producer, ahead of Saudi Arabia and Russia. Oil production has been at or near record highs in all three countries.
Oil sinks below $50 on output cut doubts
US President Donald Trump celebrated the low prices. "Do you think it's just luck that gas prices are so low, and falling? Low gas prices are like another Tax Cut!" he wrote on his official Twitter account on Tuesday.
Adding to concern about a slowing global economy, a series of purchasing managers' indices for December mostly showed declines or slowing manufacturing activity across Asia, the main growth region for oil demand.
The signs of rising production illustrate the challenge facing the OPEC and its allies, including Russia, which are seeking to prop up the market with a supply cut of 1.2 million barrels per day.
However, the energy minister for the United Arab Emirates, an OPEC member, said on Tuesday he remained optimistic about achieving a market balance in the first quarter.
COMMENTS
Comments are moderated and generally will be posted if they are on-topic and not abusive.
For more information, please see our Comments FAQ