In a press statement, FPC said the nine individuals are accused of trying to smuggle weapons into Addis Ababa to disrupt Irreechaa, an ethnic Oromo thanksgiving festival celebrated in early October.
The statement further called on the public to remain vigilant against any destructive acts during the Irreechaa celebrations planned to be held in Addis Ababa this weekend.
The statement did not mention the identity of the suspects, as well as when the suspects and the weapons were caught by police.
The festival, celebrated every year at Bishoftu city, about 45 km south of Addis Ababa, is part of an ancient indigenous festival cherished by Oromos who make up about a third of Ethiopia's estimated 105 million population.
The Ethiopian government has planned this year to hold Irreechaa festival both in Bishoftu and Addis Ababa which are expected to be attended by millions of people.