Greens senator Richard Di Natale says MPs have been told to keep the blinds to their Parliament House offices closed because of the risk of a sniper attack.

Senator Di Natale said the warnings were over-the-top, and followed a ramp up of security measures at Parliament House due to fears of a terrorist attack.

The new measures will see heavily-armed police officers become a commonplace sight in and around the building, after Speaker Bronwyn Bishop told a briefing that authorities were "responding to real threats".

"Is this real? Is what is going on here real? Is there some sophisticated terror plot within the Australian community that means we will come to grief?" Senator Di Natale said.

"We had a briefing in the Australian Parliament suggesting we couldn't open our blinds from risk of sniper attack."

But crossbench colleague Bob Day said he had not heard about the warning to close his office blinds.

"No-one's told me that and I haven't been keeping my blinds closed, I think that's probably a little bit over the top, but if Senator Di Natale has been told that, well I'll leave that for him. But certainly no-one's told me that," he said.

Security at Parliament House was handed over to the Australian Federal Police last weekend, and Mrs Bishop said an AFP commander and superintendent were in charge.

Wednesday's security briefing heard there would be a more visible presence of officers with weapons - including assault rifles - both inside and outside the building.

"The need to have 'long arms' in the building is also very necessary," Mrs Bishop said.

"They are not machine guns, they are assault rifles and as such are semi-automatic.

"But it's necessary to have that degree of weaponry, not just pistols."

Officers in plain clothes will also patrol the area.

The changes represent some of the tightest security ever in place.

"One of the problems with this building of course was that it was designed for people to come in easily," Mrs Bishop told the briefing.

"And so we have lots of entrances, [you can] walk on the roof."