Oil futures slipped in Asian trade on Friday after hitting resistance at the $50 a barrel mark as investors worried higher prices could reactivate shuttered crude output, adding to global oversupply.

Prices were also pressured by a strong greenback that was buoyed by generally positive US economic data amid growing expectations of a near-term rate hike.
Brent fell 36 cents, or 0.7 percent, to $49.23 by 0602 GMT on Friday, retreating further from the previous session's $50.51 peak, its highest since early November.
U.S. crude dropped 35 cents, or 0.7 percent, to $49.13 a barrel after touching $50.21 on Thursday, it's highest since early October.
Oil pushed through $50 for the first time in around seven months on Thursday after supply disruptions from Canadian wildfires and attacks in Libya and West Africa helped cut daily output by 4 million barrels, but eased to close down on the day.
"Shale is the new shock absorber to the market," said Tony Nunan, oil risk manager at Tokyo's Mitsubishi Corporation.
"There is a wide range of production costs. Shale's total production costs are around $48-$50 a barrel - there will be producers who make money at $50," Nunan said.
Oil prices, which have risen nearly 90 percent from 12-year lows hit earlier this year, face pricing barriers to moving higher in the next three to five weeks, technical analysts said on Thursday, with Brent facing a significant hurdle at around $52 a barrel.
"In the next few months oil prices could stay in the high $40-$50 mark. We are entering the US driving period so seasonal demand might provide underlying support to oil prices," said Yvanne Lai, senior analyst at National Australia Bank.
Investors were also awaiting the appearance of US Federal Reserve Chair Janet Yellen at an event later on Friday for further indications on when the Fed could raise interest rates.
A meeting of the oil producer's cartel, the Organization of the Petroleum Exporting Countries on June 2 may give further direction to oil markets, Nunan said.
"Most people feel the meeting will be neutral or bad," he said, with a neutral outcome leading to no change in oil output, while moves by producers like Saudi Arabia to boost production, would be bad.
"The Fed meeting could be the bigger trigger. An increase in interest rates will mean a higher dollar, a higher dollar means more expensive crude which could trigger a commodities sell-off."
A raft of Fed officials have called for a normalisation of interest rates as the US economy and inflation rise, with the odds of a June hike now around 34 percent, compared with 4 percent last week, ANZ analysts said.