WASHINGTON — Rates on 30-year mortgages jumped this week to the highest level since mid-March as investors began to worry about what the Federal Reserve will do to combat growing inflation pressures.

Freddie Mac, the mortgage company, reported yesterday that 30-year fixed-rate mortgages averaged 6.08 percent this week. That was up from 5.98 percent last week.

It was the highest level for 30-year mortgages in 11 weeks, since they averaged 6.13 percent the week of March 16.

Analysts attributed the increase to rising concerns in financial markets about what the Fed might do to battle increased inflation pressures.

Financial markets this week pushed the yield on 10-year Treasury bonds above 4 percent for the first time in five months.