Australia's Prime Minister Tony Abbott made surprise visit to Afghanistan and used the opportunity to end a long-standing war.

In a special ceremony at the Australian-run base, Tarin Kot in Uruzgan province, Mr Abbott told military troops from various nations and Afghan leaders that the war in Afghanistan is "complicated."

The conflict in Afghanistan began as a mission to hunt down members of Al Qaeda in 2001 then gradually became a fight against Taliban forces. This led to the dangerous and complicated mission to rebuild the nation.

The timing of his first visit as Prime Minister to Afghanistan has given Mr Abbott the chance to declare an end to Australia's longest military engagement. Mr Abbott said the longest war of Australia has finally reached an end.

He describes the end of Australia's war with Afghanistan not as victorious or in defeat but with the hope that Afghanistan has improved with the aid of Australia. Tony Abbott said the return of troops to Australia will be bittersweet as families will welcome their sons and husbands home while others mourn for the loss of their family members.

More than 20,000 Australian troops have served in Afghanistan out of which 260 were wounded while 40 died in action.

Direct action plan rejected

Meanwhile, leading economists have rejected the direct action climate change plan of Tony Abbott and expressed their support for carbon pricing.

In a survey conducted by Fairfax Media, most economists were in favour of the current carbon pricing scheme to reduce Australia's greenhouse gas emissions. World renowned Australian economist Justin Wolfers of Brookings Institution said he will be surprised if any economist would find Mr Abbott's direct action plan effective.

If implemented, the plan will allow the government to pay for emission cuts from the agriculture and business sectors using a $2.88 billion budget in four years.

Professor Wolfers said the direct action plan will disrupt the economy more but with a limited environmental benefit than the current emissions trading scheme.

Mr Abbott's Coalition government is planning to repeal the carbon pricing scheme in November as the debate continues on whether or not the NSW bushfires were linked to climate change.

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