ADF member injured during G20 preps

An Australian Defence Force member has been injured during a G20 training exercise in Brisbane.

Defence says the injury occurred during an exercise on Wednesday.

"The member received immediate first aid and was transported to a civilian hospital where he remains in a stable condition," Defence said in a statement on Thursday.

Defence says it will not provide any further details of the member's medical condition or their service history.

It will also not comment further on what the training exercise entailed.

RAAF Super Hornet aircraft and about 2000 Defence personnel will provide security for the G20 summit later this month.

The federal government has budgeted $15 million over two years for the unprecedented security effort to protect the leaders of 20 nations as well as thousands of officials and business chiefs.

The operation includes air protection, counter-terrorism and some search capabilities including vehicles and boats.

Radar surveillance and anti-aircraft weaponry will also operate.

Earlier this week, security forces wearing body armour and carrying what looked to be fully automatic weapons were spotted carrying out a counter-terrorism operation in Brisbane's CBD.

Witnesses reported seeing about 50 officers, dressed in commando-style uniforms, engaged in the exercise.