CANBERRA, Australia -- Visitors who wear face veils to Australia's Parliament House have been restricted to sound-proof enclosed galleries usually reserved for noisy school groups under a new counterterrorism security measure announced on Thursday.

Some senators accused the Parliament of sending a message that Muslim women can be treated as second-class citizens.

The government department that runs Parliament House said in a statement that "persons with facial coverings" would no longer be allowed in the open public galleries of the House of Representatives or the Senate. They would be directed to the higher galleries where they could sit behind sound-proof glass.

From there, they cannot be seen or heard by the lawmakers.

"This will ensure that persons with facial coverings can continue to enter the chamber galleries without needing to be identifiable," the Department of Parliamentary Services said.

The change had been made "in light of the increased threat environment," the statement said.

Sen. Christine Milne, leader of the minor Greens party, described the new measure as appalling.

"This decision gives a signal to the whole country that it's OK to treat Muslim women as second-class citizens and it is not. It's wrong," Milne told reporters.

The controversy comes as the government attempts to assure Australia's Muslim minority that tough new counterterrorism laws and police raids on terror suspects' homes in recent weeks were directed at crime, not any particular religion.

Security has increased at Parliament House since the government stepped up terror warning to the second-highest level on a four-tier scale last month in response to the domestic threat posed by supporters of the Islamic State group. Security agencies say extremists have recently discussed Parliament House as a potential target for terrorist attack.

A number of lawmakers have called for full-length burqas and niqabs that cover the face to be banned from Parliament House on security grounds.

Prime Minister Tony Abbott said Wednesday he found the burqa "a fairly confronting form of attire and frankly I wish it was not worn."

But he said he was not aware of anyone attempting to enter the building wearing a burqa in the 26 years since it was opened.