Inflation in the last Iranian month of Ordibehesht ending May 20 was 25.3 percent, up from 24.2 percent in the previous month, the bank said in a statement.
The figures confirm that prices are continuing to rise sharply in Iran, with the poor hit hardest by increases in the prices of basic foodstuffs, goods and property.
Ahmadinejad has been blamed by many economists for directly fuelling the price rises by ploughing huge amounts of cash into the economy to fund local infrastructure projects.
There has been a sharp increase in money supply growth — a key indicator of future inflation trends — to almost 40 percent during the years of the Ahmadinejad presidency.
The latest criticism came from one of the country's most respected clerics, Ayatollah Nasser Makaram Shirazi who said that "the bad management in the economic affairs of the country is perfectly clear."
"Inflation is one of the problems of the people and the officials need to solve this as soon as possible," newspapers quoted him as saying.
Ahmadinejad was elected in 2005 on a platform of making the poor feel the benefits of Iran's massive oil wealth, and he has made implementation of economic "justice" the main government slogan.
He is expected to seek a second four-year term in a presidential poll next year against a background of rising discontent over inflation.
