Labor has reiterated its commitment to consider any United States request to send more troops to Afghanistan but its Defence spokesman suggests having a large number of soldiers there is unsustainable.
US President Donald Trump last week outlined a plan to combat the resurgence of the Taliban and said he would call on allies to do more.
Prime Minister Malcolm Turnbull has said Australia will consider the merits of any request to boost its contribution beyond the 300 military training and support staff now in Afghanistan.
Labor Defence spokesman Richard Marles noted on Sunday Australia was the largest non-NATO contributor to efforts to strengthen the Afghan government and military.
Australia largest non-NATO contributor
"I firmly believe that we need to be playing our part in Afghanistan and that needs to be commensurate with our size and our capabilities and our ability to do what we can," he told ABC TV.
"I think it's also important to note that what we're doing now is much more sustainable - if I can put it that way - than perhaps has been the case in the past."
The number of Australian troops in Afghanistan peaked at almost 1600 in mid-2009.
Reports suggest the US will boost its 8400-strong forces in Afghanistan by 4000, but Mr Trump did not confirm this when announcing the new plan.
