Prime Minister Malcolm Turnbull has referred to the deadly Manchester arena blasts as an attack on 'innocence'.
"This incident, this attack, is especially vile, especially criminal, especially horrific because it appears to have been deliberately directed at teenagers," Mr Turnbull told parliament on Tuesday.
"This is an attack on innocence. Surely there is no crime more reprehensible than the murder of children."
Consular officials in London are trying to establish whether any Australians are amongst the 19 dead or 50 injured in the blasts.
"We stand in this chamber offering our sympathy and support to those confronting horrific attacks like what we've seen today," Mr Turnbull said.
"Australia stands with Britain in resolute solidarity - partners in freedom's cause."
Mr Turnbull has spoken to counter-terrorism co-ordinator Tony Sheehan, Australian High Commissioner in London Alexander Downer as well as the British high commissioner in Canberra.
UK agencies are treating the blasts as a potential terrorism event.
Labor leader Bill Shorten reflected on the pain of parents.
"You think when your kids go to listen to music, they would be safe. My eldest two are teenagers, they go to concerts," he told MPs.
"I can only begin to imagine the pain of parents wondering where their kids are when the first reports come out and the first texts and they realise that their family, their kids are at this concert."
He said his heart broke for those parents whose calls are being unanswered and the messages going through to that voicemail.
Australians concerned about friends or relatives in the UK should phone the Department of Foreign Affairs and Trade consular help line: 1300 555 135.