Spain is having to pay sharply increased interest rates to borrow ¤2.4 billion ($3.21 billion) from bond markets as investors remain cautious about a downgrade and financial difficulties, according to AP. The central bank said Thursday the treasury sold ¤1.8 billion in 10-year bonds at an average interest rate of 5.4 percent, up from 4.6 percent in the last such auction Nov. 18. It was obliged to pay a rate of 6 percent to sell ¤618 million in 15-year bonds, up from 4.5 percent in October. Demand was strong, however, almost double the amount on offer for the 10-years and almost triple the sum for the 15-years.