Oil prices were down in Asia today as caution set into the market ahead of a US crude inventory report. New York's main contract, light sweet crude for delivery in May dropped 24 cents to 93.96 US Dollars a barrel andBrent North Sea crude for May delivery shed 12 cents to 106.11 US Dollars .Analysts expect the US Department of Energy's weekly petroleum stockpiles report to show another increase in supplies which would mirror weaker demand in the world's biggest economy and put downward pressure on prices.Prices had risen at the start of the week driven by strong Japanese equities, a subdued inflation report from China and a weaker dollar.