Madonna has canceled plans to tour Australia.

The 53-year-old singer was expected to play in Sydney and Melbourne early next year - although no dates had been confirmed - but she will now wind up her tour in support of new album MDNA in December.

"Madonna's tour will end in South America in December as planned. That's all we can say," a spokesperson said. Stadiums in the two cities were believed to have been booked prior to the canceled plans.

Meanwhile, the singer began the latest leg of the tour in the UK at London's Hyde Park on Tuesday night. Madonna opened with a performance of single "Girl Gone Wild" before playing an MDNA-heavy set, occasionally airing classic tracks including "Papa Don't Preach," "Express Yourself" and "Like a Prayer."

While she has twice unveiled her breast during performances, the London show was more sedate, although she did briefly pull down her trousers to reveal her buttocks.