Australia should consider increasing its overall refugee intake as part of the debate over the humanitarian crisis in Iraq and Syria, Bill Shorten says.

The opposition leader said on Tuesday he was consulting his colleagues to determine the right size of the annual humanitarian intake.

The former Gillard government increased the number of places from 13,750 to 20,000, in line with the recommendations of an expert panel headed by the former defence force chief Angus Houston. The Abbott government subsequently reversed that.

The immigration minister, Scott Morrison, announced last month that the government would set aside 2,200 places each for Syrians and Iraqis, within the overall 13,750 humanitarian intake in 2014-15.

Shorten, who has strongly backed the government’s decision to commit to a military role for Australia in Iraq, suggested other forms of humanitarian assistance in Iraq and Syria.

“Perhaps it’s time to discuss do we take more refugees from these countries,” he told the ABC. “I think that when we look at the fact that we’re having military, potentially military operations, humanitarian relief comes in many forms but not the least of which is support for refugees to come to Australia, especially if they can’t live in their old towns and villages.”

Asked whether he would like to see an increase in the overall humanitarian intake to 20,000 places, Shorten said: “I won’t give a final number until I’ve consulted my colleagues but that’s in the right direction.”

This view is consistent with Shorten’s position before the Labor leadership ballot in September last year.

At a media conference on Tuesday, Shorten said Australia should be aware there were millions of refugees throughout the Middle East.

“There are over a million people in Lebanon, there’s a million refugees in Jordan. What we see here is a humanitarian crisis which has been going for some time,” he said.

“I’ll be talking to my colleagues about whether or not Australia can take some more refugees. Our humanitarian assistance shouldn’t just take the form of aeroplanes; it should take the form … of more foreign aid to help people who are dislocated by these evil acts, and also possibly refugees in Australia.”

Tony Abbott said the government had already taken “a very strong step in the direction that the opposition leader is keen on”.

“Because we have largely succeeded in stopping the boats, because we don’t have illegal arrivals by boat filling our humanitarian intake, we are able to now provide places to people who are stuck in camps abroad and what we’ve already announced is that there will be an additional 4,400 places available to people who have been displaced by the [Isis] advance,” the prime minister said on Tuesday.

The Greens vowed to introduce a bill during the next parliamentary sitting to return the intake to 20,000 places, and called on Labor to support it.

The Greens senator Sarah Hanson-Young said the increasing humanitarian crisis in the Middle East required “a genuine, compassionate response”.

“Waging war while refusing to increase our refugee intake is grossly irresponsible,” she said.