Brent oil dropped to a four day low after the fall in euro-area's manufacturing output and services added to concern that demand for crude would continue to decline in the region. Brent for June delivery plummeted $1.61 to $98.78 a barrel and the volume of all futures traded was 24% above the 100-day average. Prices slid 11% this year. Meanwhile WTI for June settlement plunged to $87.85 a barrel, however, might resume its decline.