The key witness in the murder of the politician Boris Nemtsov, Hanna Durytska has said that she will probably have to be questioned with a lie detector.

"I might have to do the polygraph test. So the investigator told me," Durytska said on the Ekho Mozkvy radio on Monday.

She added that she was again summoned by investigator today for further questioning.

Meanwhile, Durytska's lawyer said his client will not be giving any evidence with a lie detector, given her stressful psychological state.

"Our position is this: since no new evidence will be given, and only the truthfulness is being tested, and no one doubts the truthfulness of her testimony, we are refusing the polygraph test. She is currently in a difficult psychological situation, this is stress as well," lawyer Vadim Prokhorov told Interfax on Monday.