Mexico's central bank chief Agustin Carstens said on Friday a rise in food prices that has driven up inflation was transitory and would be difficult to contain with monetary policy.

"These are transitory issues," he said at an event in Mexico City, referring to a recent spike in the cost of eggs and other agricultural products.

Mexican inflation has been pressured by higher fresh food prices, partly due to an outbreak of avian flu, that has driven the annual inflation rate further and further above the central bank's 4 percent limit in the past four months.

But the spike in inflation may have peaked. The annual inflation rate is expected to ease to 4.66 percent in early October, according to the median forecasts of 10 analysts surveyed by Reuters.

Inflation rose to a 2-1/2 year high of 4.77 percent in September, but the market and economists do not expect a rise in interest rates any time soon.

Mexican policymakers have argued that tighter borrowing conditions have little impact on prices driven higher by a lack of supply.