Prices have fallen more than 20 per cent from their levels in early January, which they last touched in the summer of 2015. A decline of more than 20 per cent from a most recent high is typically considered a bear market.

U.S. crude for July delivery lost 97 cents, or 2.2%, to $43.23 a barrel on the New York Mercantile Exchange, trading at prices it hasn't settled below since Aug. 10. A settlement at $43.56 a barrel or lower put oil into a bear market, which means it has lost 20% or more since the recent high, a nearly one-year high on Feb. 23.

Brent futures were up 4 cents at $46.95 at 0214 GMT. On Monday, they fell 46 cents, or 1 percent, to settle at $46.91 a barrel. That was their lowest since Nov. 29, the day before the Organization of the Petroleum Exporting Countries (OPEC) and other producers agreed to cut output for six months from January. U.S. West Texas Intermediate crude futures were down 1 cent at $44.19 a barrel. They declined 54 cents, or 1.2 percent in the previous session, to settle at $44.20 per barrel, the lowest close since Nov. 14. The July contract will expire on Tuesday and August will become the front-month.

Brent crude oil LCOc1 was up 48 cents at $48.34 a barrel by 12:17 p.m. EDT. U.S. crude CLc1 was 39 cents higher at $46.04 a barrel. U.S. crude and Brent benchmarks remained on track for weekly declines of more than 3 percent, pressured by big U.S. inventories and heavy worldwide flows.

At the New York Mercantile Exchange (Nymex), the July 2017 contract price fell 5¢ from $3.071/MMBtu last Wednesday to $3.020/MMBtu yesterday.

Brent crude LCOc1 was up 43 cents by 0900 GMT at $48.49 a barrel, having fallen 4 percent the day before, while U.S. crude futures CLc1 rose 38 cents to $46.10 a barrel.

Brent crude prices LCOc1 were at $49.70 per barrel at 1351 GMT, down 42 cents. Brent is about 8 percent below its open on May 25, when OPEC and other producers agreed to extend oil output cuts through to the first quarter of 2018. U.S. light crude prices CLc1 were at $47.69 per barrel, down 50 cents.

EIA forecasts Brent spot prices to average $53/b in 2017 and $56/b in 2018.

The US Energy Information Administration lowered its crude-oil price forecast and raised its US production outlook for 2018. The lower price forecast reflects the possibility of a return to modest oversupply in global oil markets in 2018.

Global benchmark Brent LCOc1 advanced 1.1 percent to $50.48 a barrel. U.S. oil CLc1 also climbed 1 percent to $48.17.

A crude price in the $50s is the new reality for bosses of some of the world’s largest producers as output caps from OPEC and its allies are balanced out by rising U.S. shale.

Benchmark Brent crude futures LCOc1 were off by nearly 3 percent at $49.14 per barrel at 1034 GMT (6:34 a.m. ET), down $1.49 from the previous close. U.S. West Texas Intermediate crude CLc1 futures fell $1.45 cents to $46.91 per barrel.

US crude oil inventories fell for an eighth straight week and drawdowns appear to be expanding.

Pumping crude from seabeds thousands of feet below water is turning cheaper as producers streamline operations and prioritize drilling in core wells, according to Wood Mackenzie Ltd. That means oil at $50 a barrel could sustain some of these projects by next year, down from an average break-even price of about $62 in the first quarter and $75 in 2014, the energy consultancy estimates.

Benchmark Brent oil LCOc1 was down $1.45, or 2.8 percent, at $50.39 a barrel by 1157 GMT (7.57 a.m. ET), after earlier touching $50.13 a barrel, the weakest since May 10. U.S. light crude CLc1 traded at $48.43, down $1.23 cents, or 2.5 percent.