A catalyst component for the polymerization of olefins, comprising Ti, Mg, halogen, an electron donor (ID) selected from the group consisting of aliphatic cyclic ethers and alkyl esters of aliphatic monocarboxylic acids and a compound of a metal selected from the group consisting of Zn and Cu, wherein the catalyst component is devoid of Zn—C or Cu—C bonds and the Mg/Ti molar ratio ranges from 4.0 to 50.0.