Prime Minister Malcolm Turnbull has arrived in Malta for the Commonwealth Heads of Government Meeting where climate change is expected to top the agenda.

Mr Turnbull flew in on an RAAF plane on Friday morning and later headed to the Mediterranean Conference Centre in the capital Valletta for the CHOGM opening ceremony, which is to be presided over by the Queen.

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Heavy security is in place on Malta, with armed soldiers meeting all flights bringing in Commonwealth leaders.

Mr Turnbull, an avowed republican, will meet the Queen at a luncheon for new Commonwealth leaders on Friday before attending a CHOGM executive meeting where a new secretary-general will be officially chosen.

There’s been speculation that former coalition foreign minister Alexander Downer could be given the post.

Mr Downer, who is Australia’s high commissioner in London, has been in Malta over the past few days standing in for Julie Bishop at a meeting of Commonwealth foreign ministers.

After the new secretary-general is announced, Mr Turnbull will attend a special session on climate change along with special guests, UN head Ban Ki-moon and French President Francois Hollande.

The CHOGM leaders’ retreat is being held on Saturday, with 53 nations represented .

Mr Turnbull flies from Malta to Paris on Sunday for key talks to reach a global agreement on tackling climate change.

He told ABC’s 7.30 program on Thursday he was “optimistic” of a good outcome in Paris where he will promote Australia’s policy to cut emissions by 26 to 28 per cent on 2005 levels by 2030.

Labor leader Bill Shorten on Thursday announced a more ambitious goal to achieve a 45 per cent reduction by 2030, prompting government frontbencher Christopher Pyne to label the proposed policy “mad”.

– AAP