The legal age a soldier can be sent to a combat zone is 18.
The shadow home secretary made the gaffe ahead of the second reading of a private members’ bill seeking to reduce the voting age to 16 on Friday.
“The Labour Party believes young people should have a say over their future”, she says.
British Army soldiers can sign up at the age of 16 but they cannot be sent to fight in a war zone or engage in a hostile situation until the age of 18.
One person criticised Ms Abbott on Facebook, writing: “You can’t fight at 16. You can join the forces but definitely no fighting until you’re 18. That is international law. Straight away wrong with a simple fact.”
Another joked: “She was never good with numbers.”
James tweeted: “Thankfully 16 year olds are not allowed to fight for their country @HackneyAbbott.”
Another person said: “You have probably just upset a lot of 16 year olds that they may have to go to war.”
A man wrote: “Sixteen year olds don’t fight on the frontline… yet again Abbott doesn’t know the facts.”
It comes after Ms Abbott floundered over Labour’s plans for police funding during two separate interviews during the election campaign saying hiring 10,000 police officers can be funded with £300,000 a year which means each police officer earns £30 a year.