The European Union is tightening sanctions against Iran, concerned about alleged violations of human rights in the country.

EU foreign ministers, meeting Monday in Brussels, added nine people they said were "responsible for serious human rights violations" to the list of those subject to a travel ban and an asset freeze, bringing the number of people sanctioned in this way to 87. The foreign ministers also decided to freeze the assets of one "entity," meaning a company or organization.

The measures will be valid until April 13, 2014. The names of those sanctioned will be published Tuesday.

Iran carried out at least 55 public executions in 2012, U.N. spokeswoman Cecile Pouilly has said. Some 400 people were reportedly put to death in the country last year.