Lady Gaga sang a few bars of her hit Born This Way and demanded gay rights worldwide at a rally in Rome's ancient Circus Maximus.

The eccentric singer defined herself as a "child of diversity" and called for an end to intolerance and discrimination against gay and transgender people in many countries.

Lady Gaga proudly cited her Italian roots, played the piano and sang at the end of a gay pride parade.

She told fans that her costume - a one-shoulder black top and flouncy black-and-white plaid skirt - were from Gianni Versace's last fashion collection.

Lady Gaga insisted gays "will not be treated as anything less than human".

She said thousands of people attended the rally "to defend love".