CANBERRA: Malcolm Turnbull, an urbane former investment banker who supports marriage equality and action on climate change, was sworn in as Australia's 29th prime minister on Tuesday, a day after ousting longtime rival Tony Abbott in a party room coup.

Turnbull, a Rhodes Scholar who previously led the Australian Republican Movement, was sworn in by Governor General Sir Peter Cosgrove, the representative of Britain's Queen Elizabeth, Australia's head of state.

Turnbull's Liberal Party and its junior coalition partner the National Party won a landslide election in 2013 but Abbott was jettisoned by his party after a series of perceived policy missteps and destabilising infighting.