TRAIN commuters may be subject to full-body scanners during the G20 Summit in Brisbane, a security expert has warned.

ARC Centre of Excellence in Policing and Security director Simon Bronitt said train and bus lines through South Bank were a potential threat to world leaders at the Brisbane Convention and Exhibition Centre and may have to be closed.

"Obviously public infrastructure is always a target and a decision will have to be made about whether these lines stay open during the summit," he said.

"'I was travelling recently on the Beijing tube and they actually use full body scanners before you enter every tube station. That measure seems appropriate in this situation."

Every weekday, 318 trains pass through South Bank railway station, coming within 5m of the conference location.

The South East Busway also passes within metres of the centre, but while buses can be redirected through suburban street routes there is no alternate train route to get from the north to south of the city.

Closing nearby South Bank stations or installing body scanners would cause huge logistical problems for transport authorities and major headaches for commuters.

Full-body scanners also caused controversy when the Federal Government announced they would be adopted in Australia.

Civil libertarians were concerned the scanners created a near-naked representation of the body.

Transport Minister Scott Emerson said public transport security would be assessed ahead of the summit.

"My department will be working with security agencies to ensure appropriate and sensible measures are in place during the G20," he told mX.

For those wanting to catch a glimpse of the likes of US President Barack Obama, Bronitt had some advice: "You'll get a better look on the television at home. They'll be whisked from their hotels to the location in bulletproof limousines and I'd highly doubt there'd be any public appearances.'