Employees of The New York Post,Rupert Murdochs irreverent and hard-charging city tabloid,were told Friday to keep any documents that may pertain to the kind of illegal activity that has led to arrests and a widening investigation at the News Corps UK papers. An e-mail to Post journalists on Friday said News Corp lawyers had ordered them not to discard anything that relates to any unauthorised access of personal data or payments to government officials. The directive was the clearest sign yet that the companys lawyers believe the scope of two early-stage investigations in the US could broaden.