The Australian prime minister, Tony Abbott, has stepped back from his earlier promise to “shirtfront” the Russian president, Vladimir Putin, over Moscow’s response to the downing of Malaysia Airlines flight MH17, saying that the incident is just one of many subjects that will be discussed at upcoming top-level international conferences.

Abbott and Putin are both in Beijing for the Asia Pacific Economic Cooperation (Apec) meeting, and are expected to meet separately for closed bilateral talks. Putin will also travel to Brisbane for the G20 meeting next weekend.

“There is a big agenda here and conversations with the Russian president on a very important subject are only part and by no means the biggest part of the agenda that Australia is following here in Beijing and subsequently in Brisbane,” Abbott told reporters on Monday.

“Russia has said that it will do everything to bring the perpetrators [of the downing of MH17] to justice. Good on Russia for saying that and I will just be looking for an assurance from the president that what they said then, they meant, and what they said then is still what they say now.”

Abbott has steadily downgraded his vow to “shirtfront” Putin over his handling of the shooting down of the Malaysian plane in July. Upon arriving in Beijing, he promised “robust discussions” with Putin.

Foreign minister Julie Bishop defended Abbott’s use of the sporting term, saying on the weekend that “since the phrase shirtfront was used, I understand it’s now entered the diplomatic lexicon of many countries”.

But it drew jeers from the opposition.

“Tony Abbott’s got himself into a real situation here where he overreached and said that he would shirtfront the Russian president and clearly he’s not going to shirtfront him. I don’t even think Tony Abbott knew the AFL term … what shirtfronting meant,” the opposition leader Bill Shorten told reporters on Monday.

He wants the prime minister to “get answers” over the MH17 incident, which killed nearly 300 people, including 38 Australian citizens and residents.

“Unfortunately, I don’t think the Russian government will be forthcoming even though they’re the people who know most about the separatists in eastern Ukraine who may well have shot down this plane,” Shorten said.