The invention relates to biodegradable nano-polymer compositions, or nanocomposites, comprising poly(lactic acid) and co-polyester polymer with adipic acid compounded with nanoparticles of a mineral material having a degree of purity of at least 99.9%, preferably 99.99%, selected from the group of silica and magnesium silicate. In addition, the present invention refers to a process for manufacturing the said compositions as well as biodegradable articles made on the basis of such compositions, such as molded, formed and extruded articles.