(Reuters) - Russia said on Monday it planned to attack Ukrainian arms factories in retaliation for what it said was a Ukrainian strike on the separatist-controlled city of Donetsk, and urged workers and local residents to stay away.

       The defence ministry noted in a statement that Russia believed Ukraine had used cluster charges on a densely populated area of Donetsk.

       It said Russian forces would respond by acting to "disable enterprises of the military-industrial complex of Ukraine that manufacture, repair and restore weapons that nationalists use to commit war crimes".

       It added: "We urge citizens of Ukraine working at these enterprises, as well as residents of nearby residential buildings, to leave areas of potential danger".

       (Writing by Kevin Liffey; editing by Andrei Khalip)