Sydney - It topped the charts simultaneously in Britain and the United States, is used to puff up national pride by airline Qantas and is consistently voted among the most popular Australian songs of all time.

It's Down Under, a reggae-inspired 1981 smash hit for Melbourne band Men at Work - and it's at the centre of a high-stakes court case that began Thursday in their hometown.

Lawyers for music publishers Larrikin Music argue the flute part is a lift from a song they own, Kookaburra Sits in the Old Gum Tree, which was written for a Girl Guides jamboree by Marion Sinclair in 1934.

Lawyers defending the band members claim copyright was never properly signed over and Kookaburra is still owned by the Girl Guides.

At stake are royalty payments worth millions of dollars from a song that was the soundtrack of Australia's successful tilt at yachting's Americas Cup in 1983 and had a place in the closing ceremony of the 2000 Olympics in Sydney. (dpa)