Oil continued to slide on Friday, with WTI trading below the symbolic $90 a barrel mark as the market clung to signs of easing in the Ukraine crisis and a return of Iran to the market. Around 11:00 GMT (12:00 CET), the price of a barrel of Brent from the North Sea for delivery in April lost 2.65% to 90.51 dollars. In New York, a barrel of West Texas Intermediate (WTI) for delivery in March, which is the last day of use as a benchmark contract, fell 2.64% to 89.34 dollars.