Oil prices slipped on Tuesday after the International Energy Agency (IEA) forecast a global supply glut would last through 2016 as demand growth slows and key OPEC producers maintain near-record output. The Paris-based IEA said the world oil market would remain oversupplied for at least another year. “A projected marked slowdown in demand growth next year and the anticipated arrival of additional Iranian barrels – should international sanctions be eased – are likely to keep the market oversupplied through 2016,” the agency said.