Paste two text lists (one list a file) into one list separated by semicolon

An example of the process/output would be: File1: ``` hello world ``` File2: ``` foo bar ``` Resulting file after concatenation: File3: ``` hello;foo world;bar ``` For a large list of non-predictive text (no-wild cards - but lines are aligned as above). I cannot figure out how to do this with the paste command under Ubuntu.