LONDON  - Gold prices fell on Monday, extending the previous session's losses, as concerns intensified over the outlook for Spain ahead of a bond auction this week, denting appetite for assets seen as higher risk and hurting the euro. Fears about Spain's ability to keep its finances under control sent the cost of insuring its debt against default to record highs, after data on Friday showed record borrowing by Spanish banks from the European Central Bank. Spot gold was down 0.3 percent at $1,653.19 an ounce at 1405 GMT, off an earlier low of $1,640.64. US gold futures for June delivery were down $5.20 at $1,655.00.