* Dollar trims early losses that boosted oil
* Concerns about global economy curb oil's early bounce
* Brent settled at lowest since April
* U.S. crude slide sends it into bear market territory (Adds U.S. crude drop into bear market territory in paragraphs 1, 2)
By Robert Gibbons
NEW YORK, July 23 (Reuters) - Brent crude oil futures settled at its lowest since April on Thursday and U.S. crude fell into bear market territory and ended below $49 a barrel for the first time since late March, as persistent concerns about ample supply and shaky demand offset support from the dollar's weakness.
U.S. crude's $48.45 a barrel settlement is down 21 percent from the June 10 close at $61.43 and a 20 percent downturn is considered by many traders to constitute a bear market.
The weaker dollar .DXY supported oil early, but the U.S. currency trimmed losses after a report showing tumbling jobless claims in the United States. USD/
A weaker U.S. dollar makes greenback-denominated oil less expensive for consumers using other currencies.
The number of Americans filing new applications for unemployment benefits last week fell to its lowest level since 1973, suggesting a continuing solid pace for job growth. ID:nL1N10317J
"The dollar recovered from its lows and there is just a negative mood in commodities and for oil there is the worry that the global economy is going to affect demand," said Phil Flynn, analyst at Price Futures Group in Chicago.
U.S. September crude CLc1 fell 74 cents to settle at $48.45 a barrel, the lowest settlement since March 31.
The session low of $48.21 was the lowest front-month intraday price since April 2.
Brent September crude LCOc1 fell 86 cents to settle at $55.27, the lowest since April 2. Thursday's $55.10 session low matched the low from July 7.
Both U.S. and Brent crude are on pace to post double-digit percentage monthly losses.
Brent's premium to U.S. crude CL-LCO1=R seesawed but increased to $7.19 a barrel intraday.
Ample supply continues to weigh on oil futures.
U.S. crude oil stocks rose 2.5 million barrels last week, according to Wednesday's Energy Information Administration (EIA) report, trumping expectations for a drop of 2.3 million barrels. EIA/S
The supply glut looks set to grow as Iran's nuclear deal with the West is expected to release millions of barrels of additional supply into the market.
Global surpluses and concern about weakness in China's economy sent copper and aluminium to two-week lows on Thursday. MET/L
The Thomson Reuters CoreCommodity CRB Index .TRJCRB , which tracks 19 commodities, fell 1.11 percent.
"We will be keeping a watch on the copper market (for) anecdotal evidence of a slowing in China's economic growth," Jim Ritterbusch, president at Ritterbusch & Associates, said in a note.
Ritterbusch pointed to the recent correlation between slumping copper CMCU3 and U.S. crude futures.