Soaring feed costs and the spread of bird flu have pushed up egg prices in Tokyo to an all-time high.

The benchmark-average wholesale price of medium-sized eggs has surged 86 percent from a year earlier. A kilogram now costs 327 yen, or two dollars and 40 cents.

That's the highest figure since 1993, when statistics were first published. It's also up 15 percent in yen terms from the previous record high marked in December.

The ministry of agriculture says egg prices normally fall after peaking in December during the holiday season. That's when demand rises from producers of Christmas-time cakes and traditional New Year delicacies.

But ministry officials are seeing a different trend this year. They note that prices of corn and other feed grains remain expensive due to the Russian invasion of Ukraine. The ongoing spread of avian flu has also reduced egg shipments.

Poultry farmers are putting priority on supplying households. That has prompted some convenience stores and restaurants cut back on products and dishes made from eggs.