[Editor's note: This story was updated at 10:20 a.m. CT March 23.]

Oil prices dipped on March 23, struggling to recover from four-month lows because of investor concerns that OPEC-led supply cuts were not yet reducing record U.S. crude inventories.

Benchmark Brent crude oil was trading at $50.31 a barrel (bbl) by 9:30 a.m. CT (14:30 GMT), down 33 cents on the day and hovering above March 22's slide to $49.71, its lowest level since Nov. 30 when OPEC announced plans to cut output.

U.S. West Texas Intermediate light crude slipped 39 cents to $47.65.

Brent remains well below this year's high above $58, reached shortly after Jan. 1 when the deal between OPEC and non-OPEC states to curb supplies by 1.8 MMbbl/d came into effect.

OPEC has broadly met its commitments to reduce output, but non-OPEC producers have yet to fully deliver on pledged cuts and U.S. shale oil producers have been pumping more oil after crude prices recovered from last year's drop below $30.

"Headwinds from rising production and compliance issues will keep the upside limited for now," said Ole Hansen, head of commodity strategy at Saxo Bank, adding that risks were "skewed to the downside" and the upside for Brent was limited to $53.

Oil ministers from OPEC and some non-OPEC states meet March 26 in Kuwait, where they are expected to discuss compliance.

Global stockpiles have risen even with OPEC-led cuts. On March 22, data from the U.S. Energy Information Administration showed U.S. inventories jumped by a bigger-than-expected 5 MMbbl last week to 533.1 MMbbl.

London-based Barclays bank offered a more upbeat outlook, saying the latest oil price weakness would not last into the second quarter. The bank forecast a modest price recovery.

"We see a rebound to the high $50 and $60 range in [the] second quarter as inventories draw and the market readies for the peak driving and demand season," the bank wrote in a note to clients.

It said inventories held by industrialized nations would be eroded by the end of the second quarter, sliding to OPEC's targeted level of the five-year average.