Barcelona superstar Lionel Messi and Real Madrid hero Cristiano Ronaldo have taken to social media to offer their sympathies to the victims of Friday's attacks in Paris.

French officials report that 128 people were killed and another 99 left in a critical condition following what appeared to be coordinated terrorist acts across the French capital.

Four fatalities were reported outside the Stade de France, where the national team was playing an international friendly against Germany.

Barcelona forward Messi posted on Facebook to offer his condolences.

"All our thoughts are with yesterday's victims and their families," the Argentina international wrote.

"We want to reiterate today, more than ever, that there's only one way: love and peace between mankind and the world will stick together to achieve it. #PrayForParis." 

Ronaldo, Real's record goal scorer, also expressed his support.

"I can't be indifferent to the horror of the Paris attacks," the Portugal star posted on Twitter. "My thoughts go to the victims and families."