A career in politics and a lifetime as a sportsman have given him the discipline and stamina needed for early starts, late finishes and difficult issues.

This week, the Prime Minister has cleared his diary and cancelled his travel plans to focus on MH17.

He has napped in his office waiting for calls from leaders overseas and convened daily meetings of the national security committee.

He has had working dinners and briefings from military and defence chiefs.

And, he has begun the sombre duty of talking to the families of victims of the MH17 tragedy.

When asked earlier this week how difficult it has been to talk to them, the Prime Minister did not respond about himself, merely saying ''I'm sure you never really come to terms with a loss of this magnitude''.

But observers of the Prime Minister would agree that the grim task of ''bringing them home'' has left him weary.

On Wednesday, in another lengthy press conference about the MH17, his bloodshot eyes betrayed the effort of the previous six days.

It has already been a long road: from the initial shock of the news, to the intensive battle to get the United Nations on side for an independent investigation and the start of the process to repatriate the dead.

Abbott has had at least 20 calls with world leaders in the wake of the disaster, including two conversations with US President Barack Obama, four with Malaysian Prime Minister Najib Razak, three with Dutch Prime Minister Mark Rutte, two with British Prime Minister David Cameron and five with Ukrainian President Petro Poroshenko.

On Thursday, Abbott's office announced he had pulled out of a major summit with Pacific Island leaders to keep focusing on MH17.The Pacific Islands Forum leaders' summit - which includes representatives of 15 other countries in the region - is due to take place in Palau from July 29 to August 1.

Deputy Prime Minister Warren Truss will now attend in his place.