In a solemn and elaborate ceremony worthy of a "Game of Thrones" pageant, women in ancient-Greek style dresses and men in tunics performed symbolic rituals at the site of Ancient Olympia.

The Games were first held there in 776 BC and remained there for 12 centuries.

She then delivered the flame to Greek world gymnastics champion Eleftherios Petrounias, the first runner in a torch relay that will conclude at the opening ceremony in Rio's Maracana Stadium.

The chief organiser of the Games, Carlos Nuzman, promised to "deliver history". He said the Olympics would unite Brazil, which is beset by political and economic crises.

Before the flame arrives in South America it will begin a six-day relay across Greece, passing through the town of Marathon - which gave its name to the long distance race - as well as a camp for refugees and migrants in Athens, the International Olympic Committee has said.

The flame is due to arrive in Brazil on 3 May for a relay across the country, travelling through hundreds of cities and villages in every Brazilian state.

It will be carried by about 12,000 torch bearers.