concrete block cutting knife source ?

Can anyone (UK) suggest a source for cutting knives 12 " or 24" long for a home brew cement block cutter? I ve previously used blades like a toblerone bar about 20mm triangular which were for cutting pavers, that source dried up . the machine works fine with such blades but im having bother finding suitable blades. machine cuts 100 or 150 mm blocks with one sharp press of a

5 foot handle, its really a beefed up version of the cheapy paver cutters available.