No, you cannot get admission into BA Public Administration directly after a 3-year diploma done after 10th, through lateral entry.

For BA courses, most universities need you to complete 12th class (10+2) . Diploma after 10th is not accepted for lateral entry into BA courses.

You may need to do 12th through open schooling (like NIOS) or join from the first year of BA if the college allows diploma holders. Better to check with the specific college or university.

Hope it helps !