I just found this in an article about the incident:
"At the 1978 world cup in Argentina, he officiated the Round 1 match between Brazil and Sweden, in which he infamously blew the whistle for full-time during a play from a corner kick, so that a potential late goal, which would have given Brazil a 2–1 win, could not be scored. He argued that the match time had run out when the kick was taken, although the rules state that an offensive play must run its course before the final whistle can be blown".
I've not looked for the rules / laws for the period. but that seems very logical