Boris Nemtsov's girlfriend has broken her public silence on the murder of the Russian opposition activist, saying she did not see the killer who gunned him down as they strolled across a bridge near the Kremlin.

Speaking largely without emotion in deadened monosyllables, Ukrainian fashion model Anna Duritskaya said she had little recollection of what happened in the moments after Nemtsov was shot dead on Friday night.

She told online news channel Dozhd that she had not noticed anything suspicious as the couple dined at a restaurant overlooking Red Square. It had not occurred to her that someone might be following them as they headed across the river toward Nemtsov's apartment.