Two Australian security contractors were injured when a car bomb was detonated near their vehicles in the Afghan capital, Foreign Minister Julie Bishop has confirmed.

Australian embassy staff have escaped injury, but two security contractors were injured in the attack in Kabul on Friday.

Ms Bishop said up to three Afghan civilians were also killed.

“Our hearts and thoughts go to the families of those injured,” Ms Bishop said.

The attack happened in a gated part of Kabul that is popular with expats and also houses a military training centre.

An Australian convoy was close when the bomb blast went off.

Ms Bishop said she was “deeply concerned” about the safety of all people in the area.

Ms Bishop previously released a statement saying no Australians were injured in the blast, but local press reported a single casualty — a child selling vegetables from a cart.

No militant group has claimed responsibility for the attack.

Kabul has endured a spike in violence in recent weeks, including a bomb planted in an ambulance which killed more than 100 people.

-ABC