Prosecutors have launched an investigation into who sent an anonymous letter promising an attack on Jaroslaw Kaczynski, the opposition Law and Justice (PiS) leader.

The letter was sent to the office of PiS MP Waldemar Andzel in Bedzin in the south-western region of Silesia. The letter writer threatens an attack with the use of explosives when Jaroslaw Kaczynski next visits Silesia.

The handwritten one page letter was sent from the nearby city of Czeladz.

Prosecutor Monika Jankowska says the letter will be examined by an expert in handwriting to obtain as much knowledge about its author as possible.

Last month an aide was killed and another seriously wounded in an attack on the Law and Justice office in the city of Lodz. (kk)