BERLIN (Reuters) - A suspicious package sent to German President Joachim Gauck's office on Friday and destroyed by police did not contain explosives, federal investigators said.

Earlier, a spokesman for Gauck said police had carried out a controlled explosion of the package, in a park next to the presidential palace in central Berlin.

Federal investigators said their tests had shown there were no explosives, despite the earlier suspicions of the bomb disposal experts.

The incident came a day after U.S. authorities charged a man with mailing letters to President Barack Obama and a U.S. senator containing a substance that preliminarily tested positive for ricin, a highly lethal poison made from castor beans.

(Reporting by Thorsten Severin; Writing by Gareth Jones and Alexandra Hudson; Editing by Alison Williams)