image copyrightGetty Imagesimage captionBarnaby Joyce has been named leader of Australia's Nationals party

Australia's deputy prime minister has been replaced in sudden leadership contest within the National Party, the junior partner of the government.

Barnaby Joyce defeated Michael McCormack in a party vote on Monday.

It follows growing concern from some National MPs over their party's influence in climate policy.

The party, which represents farmers and rural voters, has 21 members in the governing centre-right coalition.

Over the past week, National party members voiced opposition to indications from the government that it is moving towards a 2050 net-zero emissions target.

At the G7 summit last week, Prime Minister Scott Morrison displayed growing support for the target.

Critics of Mr McCormack said he had not been assertive enough about the National party's stance within the coalition.

That set the backdrop for the leadership contest which Mr Joyce reportedly won by a narrow margin.

He is expected to push for changes in the coalition agreement.

image copyrightGetty Imagesimage captionPrime Minister Scott Morrison (L) listens to former Deputy Prime Minister Michael McCormack

A well-known character in Australian politics, Mr Joyce previously led the National Party from 2016 to 2018 but was forced to resign after public pressure over his extra-marital affair with a staffer.

He is expected to be sworn in later on Monday.

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Australian politics in the past decade has been characterised by a series of party leadership contests which have unseated four different prime ministers.

media captionBarnaby's battles: Dogs and dual citizenship