The sound of multiple blasts were heard at around 1615 GMT on Monday in the centre of the city of Donetsk, which is held by Russian-backed separatists in eastern Ukraine, a Reuters witness said.
The nature of the blasts was unclear.
President Vladimir Putin told his Security Council on Monday that Russia should consider recognising the independence of two breakaway regions in eastern Ukraine, a step that would intensify its standoff with the West and Kyiv.
(Reporting by Polina Nikolskaya; Writing by Andrey Ostroukh; Editing by Jon Boyle)
