Spanish police arrested a 74-year-old man suspected of sending parcel-bombs in November and December to targets including the Ukrainian and U.S. embassies and the prime minister"s office, the Interior Ministry said, writes Reuters.

The man was detained in the northern town of Miranda de Ebro, and police searched his home. The suspect is a retired Spanish citizen with the initials P.G.P. who is tech-savvy and very active on social networks, the ministry said.

“Although it is presumed that the detainee made and sent the explosive devices by himself, police do not rule out the participation or influence of other persons in the events”, - it added in a statement.

Interior Minister Fernando Grande-Marlaska declined to comment on reports that a Russian group could be behind the attacks.

“We are working on all possibilities”, - Grande-Marlaska told reporters from Vitoria. “The investigation is very advanced and we can really be very satisfied”.