The average long-term U.S. mortgage rate rose again this week, reaching its highest level in nine months, another setback for prospective homebuyers By ALEX VEIGA AP business writer The average long-term U.S. mortgage rate rose again this week, reaching its highest level in nine months, another setback for prospective homebuyers. The benchmark 30-year fixed rate mortgage rate rose to 6.53% from 6.51% last week, mortgage buyer Freddie Mac said Thursday. Despite the latest increase, the average rate remains below 6.89%, where it was a year ago. When mortgage rates rise they can add hundreds of dollars a month in costs for borrowers, reducing their purchasing power. Rates have been mostly trending higher since the war with Iran began, disrupting the passage of tankers ferrying crude oil from the Persian Gulf to customers worldwide. That’s sent oil prices sharply higher — a key driver of inflation .…