Rates on 30-year mortgages rose for a fourth consecutive week, climbing to the highest level since late March, as financial markets continued to worry about inflation.

Mortgage giant Freddie Mac reported Thursday that the nationwide average for 30-year, fixed-rate mortgages rose this week to 5.98 percent, up from 5.91 percent last week. It was the highest level since rates rose the week of March 31 to 6.04 percent, which has been the highest nationwide average for the 30-year mortgage so far this year.

The Federal Reserve – and its chairman, Alan Greenspan, above, – last month decided to raise a key short-term interest rate it controls for an 11th time with Fed officials, saying they are more worried about the inflation threat from surging energy prices than they are concerned that the hurricanes will have a lasting effect on economic growth.