Tributes were pouring in on Tuesday morning for three French sports stars killed in a helicopter crash in Argentina. Two helicopters collided near Villa Castelli in La Rioja province, around 1200 kilometres north-west of Buenos Aires, killing eight French nationals and two Argentinians during filming for reality television show 'Dropped'.

Among those killed were Olympic swimming champion Camille Muffat, boxer Alexis Vastine and sailor Florence Arthaud, the Argentinian government said. British swimmer Fran Halsall paid tribute to 25-year-old Muffat, posting on Twitter

Muffat won gold in the 400 metres freestyle at London 2012 - ahead of bronze-medallist Rebecca Adlington - as well as silver in the 200m freestyle and bronze in the 4x200m freestyle relay.

Twenty-eight-year-old Vastine claimed light welterweight bronze at the 2008 Olympics in Beijing, while 57-year-old Arthaud was considered one of the world's best sailors.

French president Francois Hollande said in a statement published on the website of French daily Liberation: "The brutal demise of our compatriots is an immense sadness."

^{France's gold medalist Camille Muffat celebrates on the podium at London 2012. Source AFP}

Former Arsenal forward Sylvain Wiltord, a reported contestant on the reality show who was not in either helicopter, tweeted: "I am sad for my friends, I tremble, I am horrified, I have no words, I cannot say anything."

Other French sports stars also took to Twitter to mourn their compatriots.

Formula One racing driver Romain Grosjean tweeted: "Horrified to learn of the death of Florence Arthaud, Camille Muffat, Alexis Vastine and all the other people who were on board."

Tennis player Paul-Henri Mathieu posted: "Terrible ... Courage to families and friends."

Adlington said that Muffat would be "dearly missed".

The 26-year-old Briton, who won gold in both the 400m and 800m freestyles at the 2008 Olympics in Beijing, wrote on Twitter: "So sad and shocked to wake up to hear the tragic death of Camille Muffat. She was an amazing sportswoman, competitor and lovely person.

"My thoughts go out to not only all her friends and family but to all the family and friends of all the 10 victims. Its an extremely sad day.

"RIP Olympic Champion Camille Muffat. You will be dearly missed. X"