Police have detained a man outside the ministerial entrance of Parliament House in Canberra.

The incident unfolded about 12:30pm (AEDT) when police and protection officers saw the man, believed to be aged in his 30s, armed with a knife.

Officers attempted to persuade the man to hand over the knife, but when negotiations failed, he was tasered.

The man, who was restrained on the ground until an ambulance arrived about 1:00pm (AEDT), was then taken to a Canberra hospital.

Police said there were no national security concerns.

Dozens of Australian Federal Police officers surrounded the area, diverting traffic and keeping the public away from the scene.

ABC/AAP