Rwandan investigators are holding a journalist accused of receiving explosives and plotting with terrorists, the Rwanda Investigation Bureau (RIB) has said.
Phocas Ndayizera, a 39-year-old freelance journalist working for the BBC's local language service, was reported missing over a week ago before turning up in custody.
Ndayizera now faces a maximum 20-year jail term if found guilty under Rwanda's anti-terrorism laws.
"He was arrested red-handed as he received explosives, including dynamite," said RIB spokesman Modeste Mbabazi when the arrest was made public on Thursday.
"We had investigated him and linked him to terrorist groups intending to do harm to Rwanda," he added.
The RIB was established earlier this year to take over investigative functions from the police.
Paraded before the media on Thursday, Ndayizera said, "I am, up to now, not aware of the reasons why I was arrested, or the charges they have against me."
The Rwanda Journalists Association said it would not involve itself in the case since the charges do not relate to Ndayizera's work as a journalist but said it hoped he would get a fair trial.
"We are deeply concerned, given the gravity of the alleged charges, we hope he gets a fair, just and quick judicial process," it said in a statement.
The BBC's Kinyarwanda radio broadcasts were suspended in 2014 after the broadcaster ran a television documentary airing long-standing allegations that President Paul Kagame may have had a role in the shooting down of a presidential jet in 1994.
That event triggered the genocide in which at least 800,000 mostly Tutsi people were killed.
Kagame is more often praised for ending the genocide and bringing peace, stability and economic growth to his tiny country.
However, he is also criticised for suppressing dissent and the free press.