Poland's Prime Minister Donald Tusk said a man accused of plotting an assassination attack against him and his defence minister has been detained.
The interior ministry earlier reported that police had received credible information about possible attacks against Tusk and Wladyslaw Kosiniak-Kamysz.
Polish security services convened a special meeting on Sunday after receiving information about the planned attacks, with a spokesman saying officials were treating the threat as "deadly serious".
Tusk thanked the police for "swift and decisive action" in arresting the suspect.
The suspect was arrested in the Lower Silesia region and was a Polish national, Jacek Dobrzynski, a spokesman for the Special Services Co-ordinator told local media.
"In this case we are talking about a strong likelihood that these threats could actually be carried out," he said.
The plan was uncovered when an email with information about the potential attack was forwarded to police by the State Protection Service, which is responsible for ministers' security, Interior Ministry spokeswoman Karolina Galecka said.
Tusk has been Polish prime minister since 2023, having previously held the office from 2007 to 2014.
He served as president of the European Council from 2014 to 2019.