The protester climbed atop the building's crest on Monday before unfurling a "Free Assange" banner.

He told onlookers to send him up a sleeping bag, as he would only come down once Assange was released by British authorities.

But minutes later, he folded up his banner and walked across to a rooftop balcony where police took him into custody.

The 63-year-old has been charged with trespassing on Commonwealth land.

He has been bailed to appear at the ACT Magistrates Court on December 4.

Security at Parliament House is being reviewed after a the incident.

A government spokesman confirmed the presiding officers of parliament had sought an urgent briefing on the matter.

"As in all cases of security incidents, the circumstances will be reviewed," the spokesman said.

Assange, 48, is in prison in England fighting extradition to the United States.

If extradited, he could face decades behind bars on spying and hacking charges.

The Senate is sitting in Canberra this week.

Australian Associated Press