Perhaps it was nerves before being serenaded by cross-dressing Eurovision singer Conchita Wurst, but UN secretary-general Ban Ki-moon has fallen into the trap of confusing Austria with Australia during a visit to Vienna.

"I thank in particular (Austrian) president (Heinz) Fischer and the government of Australia," Mr Ban told reporters at a UN conference of developing landlocked countries hosted by the Austrian capital.

He later corrected himself and apologised in the news conference, saying: "There are no kangaroos in Austria. Sometimes this happens, I hope you understand."

Later, Ms Wurst raised the roof for Mr Ban and several hundred UN staff, belting out Cher's Believe and Rise Like a Phoenix, the song the bearded drag queen sang to win the Eurovision Song Contest earlier this year.

Ms Wurst has used her Eurovision fame to promote a message of tolerance, with performances in front of the European Parliament and at LGBT (lesbian, gay, bisexual and transgender) events around Europe.

Mr Ban paid tribute to her efforts, saying: "I will continue to fight against transphobia and homophobia. I will stand strong for equality. I hope more of you join our global Free and Equal campaign."

In an ankle-length blue dress and black high heels, Ms Wurst, 25, said to cheers: "I dream of a future where we won't have to talk about sexual orientation, the colour of your skin, your religious beliefs."

This week's UN conference of landlocked developing countries brings together 32 nations with a combined population of 450 million people looking at improving transportation networks and access to markets.

Among those present was Robert Mugabe, the 90-year-old president of Zimbabwe, and Bolivian president Evo Morales.

Neither attended Ms Wurst's performance.

AFP