Mixed economic news from the United States left crude oil prices drifting lower Thursday, though momentum could shift on any market return from Iran.

Brent crude oil prices hit $63.11 per barrel in early Thursday trading, down about a half a percent from the previous session. West Texas Intermediate, the U.S. benchmark, lost more than three quarters of a percent to $59.77 per barrel. Both indices are down at least $1 per barrel from the start of June.

Crude oil prices are up from early 2015 levels below the $50 per barrel mark as concerns about an oversupplied market ease. General global economic growth has accounted for some of the supply take-up, though momentum has been slow.

The U.S. Commerce Department said Thursday consumer spending rose 0.9 percent in May, posting its biggest monthly gain since August 2009. The Labor Department, meanwhile, said the number of claims for unemployment insurance increased 3,000 to a seasonally adjusted 271,000 for the week ending June 20. That's a second straight week of losses, though the national unemployment rate is in line with what's considered a good labor market.

On the supply side, federal data show U.S. oil production last week reached 9.6 million bpd while stockpiles continue to indicate increased demand in the domestic marketplace.

Crude oil prices collapsed last year as U.S. production pushed markets heavily toward the supply side. Members of the Organization of Petroleum Exporting Countries have vowed to keep production levels stable, however, on expectations of increased demand.

European leaders this week acknowledged they've reached out to Iran, anticipating some relief from nuclear-related sanctions. Iran is limited to about 1 million bpd in exports under existing sanctions, about half of its full potential.

Analysis from Wood Mackenzie finds Iran could add as much as 600,000 new barrels per day to the global market by the end of 2017 if sanctions are lifted. A gradual release of Iranian crude, however, "is not expected to have a significant downward effect on oil prices," the report said.