Many concert goers waved white handerchiefs as images of tropical birds, sun sets and butterflies were flashed on giant screens at Lisbon's Bela Vista park during the initiative, part of the "Rock in Rio-Lisbon" music festival.

Two of Portugal's three free-to-air television stations also went silent at 6:00 pm (1700 GMT), broadcasting images from the festival grounds but no sound for three minutes.

Brazil's culture minister, the world-famous musician Gilberto Gil, took to the stage after the three minutes were up and sang the peace anthem "Imagine" together with veteran Portuguese rocker Rui Veloso.

Billed as one of the biggest music festivals in the world, "Rock in Rio-Lisbon" will feature over 120 hours of music performed on three stages over two weekends, May 28-30 and again June 4-6.

Some 50,000 people turned out on the opening night of the festival on Friday to hear former Beatle Paul McCartney classics from his days as a member of the "Fab Four" such as "Eleanor Rigby" and "Yellow Submarine".

Other acts scheduled at the event, which is modelled on the original "Rock in Rio" festival which began in 1985 in the Brazilian coastal city it is named after, include Peter Gabriel and Alejandro Sanz.

Organisers say they expect 350,000 people to attend the festival -- which is being held outside Brazil for the first time in its 19-year history -- and another two billion people from more than 40 countries to view it on television.

As in the previous versions of the festival, held in 1985, 1991 and 2001, the Lisbon edition, whose slogan is "For a Better World", will seek to raise awareness of social problems and collect money for charities.

Festival organisers say they will donate between two and five percent of ticket sales to charities that support needy children.

The 200,000-square-metre (2.2 million square feet) festival grounds include a lecture theatre where concert goers can watch documentaries or discuss world peace in between musical acts.

WAR.WIRE