An 18-year-old Hampton Park man, who was being held by police on a preventative detention order, was charged with conspiracy to commit acts done in preparation for, or planning, terrorist acts.

He is due to face Melbourne Magistrates Court on Tuesday.

Hallam man Sevdet Ramdan Besim, 18, was charged on Saturday with the same offence. He has been remanded in custody and is due to face court again on Friday.

Police have alleged that the pair was planning an Islamic State-inspired attack at a Melbourne Anzac Day event targeting police officers.

The plot allegedly involved running a police officer over and then killing him with a knife, the ABC's 7.30 program reported on Monday night.

Those behind the plot then allegedly planned to take the officer's gun and go on a shooting rampage that would have ended in their deaths, it was reported.

It has also been reported the attack was planned to seek revenge for the death of teenager Numan Haider, who was shot dead last September after stabbing two anti-terror police officers in Melbourne.

Meanwhile, a 14-year-old boy has been arrested in Britain over his links to the plan.

Lancashire police have claimed they uncovered communications between the teenager and a man in Australia.

Five men were arrested by Victoria Police in the pre-dawn counter-terrorism raids on Saturday.

An 18-year-old Narre Warren man was arrested and charged with prohibited weapons offences. He has been granted bail and will face court at a later date.

Another 18-year-old Narre Warren man has been released pending further inquiries.

Eathan Cruse, 19, who was also arrested, gave a statement to police and was released without charge on Saturday afternoon.

The young men are believed to have had close links to senior Australian jihadist Neil Prakash.

Fairfax Media understands that police are investigating the role in the plot played by Mr Prakash, 23, who is regarded by counter-terrorism authorities as the top Australian recruiter for Islamic State.

Mr Prakash, who goes by the jihadist name Abu Khalid al-Cambodi, may have had direct contact with the Melbourne men recently, forming a link between the alleged plot and the terror group causing upheaval in the Middle East.

The men arrested on Saturday have also been linked to the Al-Furqan Islamic Information Centre in Springvale South, where leaders are suspected of preaching radical ideas.

The young men were associates Mr Haider, who also attended the Al-Furqan Centre.

Hundreds of extra police will be present at Anzac Day ceremonies across Victoria on Saturday, police said. There will also be secret security operations under way at the weekend.

Acting Police Commissioner Tim Cartwright said Melbourne's dawn service would be a key focus for officers, but other events would also be closely monitored.

"We are not restricting ourselves to the dawn service nor just to Melbourne and the Anzac Day events on that day," he said.

"We are looking right across Victoria for the events that relate to Anzac Day."

Premier Daniel Andrews reassured people heading to events, including the football at the MCG, that police were working to ensure their safety.

"Whether it be at the Shrine, other events that will occur in the suburbs and regional centres and indeed at the MCG, the rugby that evening," he said.

"I'm very confident that everything that can be done, is being done to keep Victorians safe."

Meanwhile, Mr Cruse has lodged an official complaint over his treatment by the armed officers when he was arrested. His mother Anja has told the media they dragged Mr Cruse into the kitchen, where they "flogged" him, leaving behind a "pool of blood".

A Victoria Police spokeswoman said a complaint had been received regarding the treatment of one of the men arrested and it had been referred to the force's Professional Standards ­Command.

Mr Cartwright said police would meet families involved in the raids to discuss concerns raised over police force used in the arrests.