The man was arrested on a flight from Thailand to Stockholm on Saturday, on suspicion of sending threatening mail as well as attempted murder, but it was not initially known which country the attempted murder charge was from.
“The suspicion of attempted murder regards plaintiffs in the UK,” Sweden's security police Säpo revealed on Wednesday night.
The man is accused of manufacturing an item at his home in Västra Götaland before taking it abroad, according to the prosecutor.
“It was an explosive device that could have caused someone to die, but it wasn't detonated and no one was injured,” prosecutor Eva Wintzell told Aftonbladet.
He is also suspected of 26 counts of serious threatening behaviour over letters to Swedish ministers, municipal councillors and other public figures.
One of the officials to have received hate mail is Jacob Högfeldt, a municipal spokesperson in the Moderate Party in the town of Strängnäs, who reportedly received an envelope containing white powder and the message “you will die soon” last year.
The suspect was detained in absentia for the offences in April, before police finally managed to arrest him upon his return to Sweden from Thailand on Saturday.