Sir Elton John took to the stage of the Euro 2012 Kiev fan zone on Saturday for a free concert in front of tens of thousands of fans to raise awareness of AIDS in Ukraine.

The band Queen, with American Idol star Adam Lambert as the lead singer, joined John in waiving their fees for the concert.

Queen band member Brian May said he hoped the gig would create a big impression on concert-goers.

"I guess the strongest signal would be that we must not be complacent. AIDS is still a problem. It is still walking on the Earth. And complacency is our enemy. It's a wake up to say 'No', it is still there, people are still dying of AIDS. And we have to continue the fight," he said.

According to a report by UNAIDS, Ukraine is experiencing the "most severe HIV epidemic in Eastern Europe and the CIS countries," with new cases of infection rising steadily since 1999.