Turning the tables on the United States, Iran’s Foreign Ministry said Wednesday that the American authorities were holding 19 Iranian citizens on what it described as unfounded charges of sanctions violations and called for their release.

While Iranian officials have referred previously to what they call the issue of Iranians in American custody, the latest assertion was specific about the number being held and the reason they had been imprisoned.

The Iranian statement came as the United States has been pressing Iran to release three Americans of Iranian descent — including Jason Rezaian, the Washington Post’s correspondent in Tehran — and to provide information about a fourth American missing for eight years.

Anger over the imprisoned and missing Americans has been a festering issue in the estranged relationship between Iran and the United States. Talks to resolve it were held on the sidelines of the negotiations on Iran’s nuclear activities, which were concluded in July with an agreement, but there has been no further word on the prisoner issue.