A Melbourne teenager allegedly discussed packing a kangaroo with explosives, painting it with an Islamic State symbol and setting it loose on police officers.

Sevdet Ramadan Besim, 19, of Hallam, is accused of plotting an Anzac Day terrorism attack in Melbourne that would have included a beheading.

He was committed to stand trial in the supreme court on Thursday after pleading not guilty to four charges.

They included conducting internet searches of Anzac Day in Melbourne and Dandenong, engaging in communications and creating an electronic memo on his phone – all allegedly in preparation for a terrorist act.

Besim initially faced five charges, but commonwealth prosecutor Andrew Doyle withdrew one when Besim appeared in the Melbourne magistrates court on Thursday.

Besim is accused of planning to run over, then behead, a police officer.

He allegedly said he was “ready to fight these dogs on there [sic] doorstep” in online communications with a person overseas, according to court documents.

“I’d love to take out some cops,” Besim is alleged to have said. “I was gonna meet with them then take some heads ahaha.”

Police say the pair also talked generally about Australian wildlife, suggesting a kangaroo could be packed with explosives, painted with “the IS symbol” and set loose on officers.

Besim has been in custody since 18 April, when 200 heavily armed officers swooped on the city’s south-east, arresting five teens and seizing knives and swords.

Police say Besim is motivated by an extremist ideology and has expressed support for proscribed terrorist organisations, particularly Isis, which adopt a radical interpretation of Islam.

The dropped charge was one count of conspiring to prepare for or plan an act of terrorism, which carries a maximum sentence of life in prison.

Besim is due to face a directions hearing next week.