Ukrainian President Petro Poroshenko has expressed his condolences to the families of the victims who have been killed in a recent act of terror in Nice, France.

"A terrible terrorist attack in Nice. Shocked. The whole Ukrainian nation and myself express condolences to the families of those killed in France," the president tweeted in the early hours of Friday.

According to media reports, a terrorist gunman killed 84 people and wounded scores when he drove a heavy truck at high speed into a crowd watching Bastille Day fireworks in the French Riviera city of Nice late on Thursday.

The driver was shot dead after barrelling the truck two kilometers (1.3 miles) through the festive crowd on the palm-lined Promenade des Anglais.