MELBOURNE • An Australian teenager who planned an Anzac Day terror attack that involved beheading a policeman and attaching explosives to a kangaroo has been sentenced to 10 years in prison.

Sevdet Besim, 19, pleaded guilty to "doing an act in preparation of, or planning for, a terrorist act" over the 2015 plan targeting commemorations in Melbourne honouring soldiers who died for Australia.

The Victorian Supreme Court previously heard that Besim had discussed the plot in encrypted messages with a then 14-year-old British boy who masterminded the foiled plot from his bedroom in Lancashire, northern England, and was jailed for five years last October.

Justice Michael Croucher said Besim's proposed "putrid act" was aimed at intimidating the government and striking fear into the wider community. "To the vast majority of the community, it's unfathomable an 18-year-old boy planned to kill a law enforcement officer, to crash into him with a car and then behead him with a knife," he said.

"Mr Besim conducted Internet searches on Anzac Day and places where there might be memorials.

"He had... a mind corrupted by lunatic clerics. That was all he needed to commit this atrocity, and he was prepared to die trying."

Besim, who was arrested a week before Anzac Day, was an associate of Numan Haider, who was shot and killed by counterterrorism forces in 2014 in Melbourne after stabbing two police officers. Justice Croucher said Besim wanted to go to the Middle East and join the Islamic State in Iraq and Syria, but he was refused a passport and, when Haider was killed, decided "he must take up the fight... in Melbourne".

Besim's term may have seemed harsh just a handful of years ago, but must now be understood in view of recent mass casualty attacks in Europe and the United States, said Dr Greg Barton, a terrorism expert at Deakin University.

"It has to be seen in the context of realised and attempted... lone-wolf attacks in the last two years... Every month or two, there's some development which makes the unimaginable suddenly very concrete."

A handful of terror-related attacks have been foiled in Australia over the past 18 months, the authorities have said, but several have taken place, including a 2014 cafe siege in Sydney that left two hostages dead.

AGENCE FRANCE-PRESSE, REUTERS