Spanish police on Wednesday arrested a 74-year-old man suspected of sending letter bombs to the Ukrainian and American embassies and several institutions in Spain in November and December, the interior ministry said.
The man, a Spanish national, was arrested in the northern town of Miranda de Ebro and police are still searching his home, the ministry said in a statement, without giving further details.
One person was slightly injured by a letter bomb at the Ukrainian embassy in Madrid.
Spain: Mail bomb explodes at Ukrainian embassy, one injured
Between November 24 and December 2, a total of six packages containing explosives were sent to targets including Prime Minister Pedro Sanchez, government offices, a European Union satellite agency and the United States Embassy.
Spain: Prime Minister Pedro Sanchez targeted by a package bomb, including the American embassy
Russian Imperial Movement
The arrest came three days after the New York Times reported that investigators had focused their investigations in recent weeks on the Russian Imperial Movement, a radical group with ties to far-right organizations in Spain.
He is also suspected of being connected to the Russian secret services.
Spanish authorities declined to comment on the report, while a senior judicial source denied knowledge of this investigative angle.