The Premier League champions have watched the Romanian in several Serie A games lately.
The 24-year-old centre half can also play left-back and has been linked with Juventus and Barcelona in the past year.
Enlarge Prize asset: Lazio want to tie down Radu
Lazio chairman Claudio Lotito wants to insert a £17m release clause into the contract.
Marseille 1 Chelsea 0: Brandao strikes as problems pile up for AncelottiManchester City target Radu set for showdown talks with LazioCHELSEA FC