POLICE have arrested prohibited activist Ciaron O'Reilly for trying to enter the declared G20 security zone.

Mr O'Reilly told the police officers who swooped on him that he wanted to speak with US President Barack Obama about freeing Chelsea Manning.

The US soldier was imprisoned for releasing classified documents to WikiLeaks.

Mr O'Reilly was holding a "Free Julian Assange" placard when he approached the restricted area near Musgrave Park in South Brisbane.

He also read out the letter he received from Queensland Police Commissioner Ian Stewart banning him from G20 restricted areas.

Mr O'Reilly told police no one had explained to him why he was barred.

When he tried to go into the area he was arrested and taken into a paddy wagon.

As Mr O'Reilly got into the paddy wagon he called for the freedom of Ms Manning and Mr Assange, the WikiLeaks leader.

Ciaron O’Reilly
Ciaron O’Reilly