Les Bleuets are the third team to win back-to-back Under-20 Championships, joining New Zealand, who won the title for four straight years between 2008 and 2011, and England in 2013 and 2014 in defending the title, while denying Australia a first ever triumph in the competition.

In a thrilling game, the lead changed hands no fewer than seven times before France fly-half Louis Carbonel kicked what proved to be the winning penalty with 15 minutes to go at the Racecourse Stadium.

Carbonel had been the star of France's first title success on home soil last year, kicking 23 points in their defeat of England in the final.

He pulled the strings once again as France recovered from conceding the second fastest try in Under-20 final history when Mark Nawaqanitawase scored after only 49 seconds.

World Rugby chairman Sir Bill Beaumont said: "Congratulations to France on their victory in Rosario today.

"The team showed tremendous tenacity to win by such a narrow margin in what was a thrilling conclusion to this year’s Championship in Argentina.

"Their fantastic achievement of back-to-back titles shows that the future is looking bright for France ahead of Rugby World Cup 2023."

While France were celebrating, it was misery for Scotland after they were relegated to the World Rugby Under-20 Trophy for the first time after losing the 11th place play-off to Fiji, 59-34.

South Africa finished third after beating hosts Argentina 41-16 to win the bronze medal for the third tournament in a row and the eighth time in total.

Three-time champions England came fifth after beating Wales 45-26, while New Zealand finished their campaign with a 40-17 victory over Ireland to claim seventh place - their lowest ranking in the 12-year history of the Championship.

Next year's hosts Italy beat Georgia 29-17 to claim ninth place.