WASHINGTON — Attorney General Jeff Sessions failed to disclose meetings with Russian officials when he applied for security clearance because he was told not to do so by advisers and the F.B.I., a Justice Department spokesman said Wednesday.

Mr. Sessions met with Sergey I. Kislyak, the Russian ambassador to the United States, at least twice in 2016. But asked on an official government form to note any contact he or family members had with foreign governments or their representatives over the past seven years, Mr. Sessions did not include his encounters with Mr. Kislyak. It is a federal crime to make false statements or withhold relevant information on the background check form.

“As a United States senator, the attorney general met hundreds — if not thousands — of foreign dignitaries and their staff,” Ian Prior, a spokesman for the Justice Department, said in a statement. “The attorney general’s staff consulted with those familiar with the process, as well as the F.B.I. investigator handling the background check, and was instructed not to list meetings with foreign dignitaries and their staff connected with his Senate activities.”

Mr. Sessions filled out two such forms, Mr. Prior said, one last July, as he was first formally vetted by the Trump campaign, and one after the election in November.