Oil on the Nymex were flat, but Brent crude closed at a nine-month low at the start of the week, as concerns about the strength of the global economic recovery continue to cloud the market. New York's main contract settled at $US88.7 a barrel for May delivery. The European benchmark Brent North Sea crude for June delivery dipped to US$99.9 a barrel- the first time Brent closed below $US100 since July 10, 2012. On Tuesday, Brent North Sea crude for delivery in May ended at US$100.1, down by just below three dollars from Friday. News of the Boston bombings weighed heavily on WTI in post-market trade. Also, financial markets were concerned after disappointing Q1 growth data from China, following disappointing US economic data last week. China's gross domestic product (GDP) growth slowed to 7.7% in Q1 of this year.