The U.S. Justice Department has opened an investigation into potential antitrust issues related to the surging price of eggs, The Wall Street Journal reported Friday, citing people familiar with the matter.

The investigation, which is in its early stages, includes a look at whether large egg producers have worked together to raise prices or reduce supply, the report said.

The news comes as the price of eggs has soared, leading some restaurants to announce menu changes and reports of grocery stores with empty shelves. For example, Denny’s announced last month that it was passing along rising egg costs to customers in the form of a surcharge.

In the latest consumer price index report, Bureau of Labor Statistics data showed the price of eggs up 53% year over year. On a seasonally adjusted basis, the cost of eggs rose 15.2% just between December and January — this marked the largest increase in the eggs index since June 2015.

The price increases appear to be at least in part due to an outbreak of avian flu that has led egg producers to cull their populations. However, advocacy group Farm Action sent a letter last month to the DOJ and Federal Trade Commission, calling for an investigation into other causes.

CNBC has not independently confirmed that this investigation is ongoing. The Justice Department did not immediately respond to a request for comment.