Two armed teens charged over plot 'to behead an innocent person in an ISIS-inspired Sydney terror attack' - and one of them is the son of a convicted terrorist

• Two teenage terrorist suspects have been arrested in Bankstown, Sydney
• On Thursday they were charged with terror-related offences 
• Police claim they had bayonets and planned on beheading someone
• The 16-year-olds were allegedly carrying handwritten notes to ISIS 
• Police stopped the pair near a mosque as part of an ongoing investigation  
• One of the teenagers is believed to be the son of a convicted terrorist 

Two teenagers who had allegedly planned to carry out an attack on an innocent member of the public have been charged with terror-related offences.

The 16-year-old's were arrested near a mosque in Bankstown in Sydney's west on Wednesday, and were allegedly carrying handwritten notes pledging allegiance to ISIS.

Police believe the pair, one of which is understood to be the son of a convicted terrorist, allegedly bought bayonets from a gun shop before setting off to carry out the attack.

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The duo were on Thursday charged with acts in preparation to commit a terrorist act, and police said the alleged offences were 'extremely serious'.

'Those charges are extremely serious charges with the acts in preparation to commit a terrorist act with a maximum of life imprisonment,' NSW Deputy Commissioner Catherine Burn said. 

They were also charged with membership of a terrorist organisation - and police believe they had links to ISIS. 

'In respect of these two I think that they've probably had some degrees of radicalisation from potentially radicalised peers,' she said.

'This is very serious, extremely serious, and the age of these people at the age of 16 is unbelievably serious,' Ms Burn added.

The pair will face Parramatta Children's Court on Thursday. 

Earlier it was revealed Radical Muslim preacher Junaid Thorne demanded counter-terrorism police tell him 'Where are my brothers?' after they arrested the boys, who were allegedly walking to behead an innocent person with bayonets.

It is believed officers are trying to identify who was the target of the attack by examining the notes found in the boys' pockets. 

The teenagers, who were previously reported to have been walking to the Bankstown Police Station, were stopped by officers on Fetherstone Road by the Bankstown Musalla, which is an open space outside a mosque.

Police said they could not confirm if the teenagers were heading to the police station. 

Witnesses said one of the boys was seen smiling as he sat on the ground in handcuffs. 

After the pair were arrested, Muslim preacher Juniad Thorne approached officers and asked them to tell him 'Where are my brothers?', The Daily Telegraph reported. 

Thorne was held in the Supermax High Risk Management Centre in Goulburn, New South Wales, for four months for dodging counter-terrorism authorities and using a false name to fly from Perth to Sydney, ABC reported. 

Both of the men have been known to police officers for several years, Nine News reported. 

One of the teenagers, whose father has been convicted of terror-related charges, was allegedly arrested last year for not standing for the national anthem at his high school. 

The same team's family was also targeted during the Operation Appleby raids in September 2014, and launched legal action against the NSW Police.

'What really burns me from inside was hearing my mum screaming and seeing her in pain and not being able to do anything. I will remember that forever', he told Fairfax at the time. 

It is understood the teenagers were still being interviewed by police at Bankstown police station on Wednesday night, along with numerous family members.

One of the boy's mothers was seen at the police station after their arrest. 

A NSW Police spokeswoman told Daily Mail Australia there was an ongoing investigation but refused to comment further.

'Police are unable to release anything further at this time however there is no on-going threat in relation to this matter,' police said in a statement.