The present invention relates to a process for the production of ethylene polymers in a tubular reactor comprising reacting in said tubular reactor a feed composition comprising ethylene and one or more composition comprising one or more cyclic olefin wherein the cyclic olefin is a compound having the structure of Formula (I): wherein R may be a moiety comprising ≥1 and ≤10 carbon atoms; wherein R1 and R2 may each individually be hydrogen or a moiety comprising ≥1 and ≤5 carbon atoms, R1 and R2 may be the same or different; wherein ⋅ the tubular reactor may be operated at a pressure of ≥200 and ≤280 MPa; ⋅ the average reaction peak temperature may be ≥220° C. and ≤300° C.; ⋅ the composition comprising one or more cyclic olefin may be fed to the reactor in one or more feed inlet of said tubular reactor; and ⋅ said cyclic olefin may be fed to the tubular reactor in quantities of ≤1.0 mol %, with regards to the total feed composition. Such process allows for the production of ethylene polymers having a high density and a high purity.