“You are called by investigators to the State Bureau of Investigation for questioning as a witness in the manner prescribed by law,” the state bureau website said in a statement.
It is noted that interrogations involving Poroshenko will be held on January 21 and 24.
It is also specified that the interrogations of the former president are needed for the investigation of a number of criminal proceedings.
Earlier, lawyer Igor Golovan, representing the interests of Petro Poroshenko, brought subpoenas to the GBR, which he intends to hand to investigators of the department.
At the beginning of December, lawyer Andrei Portnov stated that the GDB had instituted criminal proceedings against Poroshenko about high treason for signing the Minsk agreements.