A spokesman from the Australian Sports Commission said while no additional measures had been introduced, security at the Bruce compound were now enforcing procedures which had not been previously.

All vehicles seeking access to the institute must now register with Australian Sports Commission security prior to arrival with identification passes to be visible at all times.

Security have told athletes and staff to be more aware of their surroundings and not to allow unknown people to tailgate them when attempting to gain access to buildings.

"These security measures have been in place for some time however they are being enforced to a higher degree due to the heightened alert level," the ASC spokesman said.

"Advice was provided through a general ASIO Protective Security Circular issued to all government agencies.

"These procedures will remain in place for the foreseeable future as they represent good security practice."

The spokesman said staff and athletes had been encouraged to report "suspicious behaviour" to security.

ANU's Australian Centre for Military Security and Law visiting professor and former military intelligence officer Clive Williams said the tightening of security at the AIS was most likely a precautionary measure.

"I suppose they are reviewing security with a range of different organisations and I don't believe this would be specifically related to the AIS," he said.

Mr Williams said it was unlikely national institutions like the AIS or the War Memorial would be targeted with a more likely scenario being random attacks on individuals or MPs.

ANU terrorism expert Dr Clarke Jones said he doubted whether ISIL supporters in Australia had enough sophistication or organisation to attack a national institution such as the AIS in Canberra.

"I very much doubt the AIS would be targeted as there are much easier things to go for and ISIL supporters have shown an interest small-scale high-impact messaging through random attacks, but never say never," he said.

An ASIO spokesman said the organisation would not comment on specific intelligence matters.

A National Museum of Australia spokeswoman said management "continues to review and adjust security measures as appropriate" while the Australian War Memorial refused to comment on whether they had increased security.

A  National Library of Australia spokeswoman said the library monitors advice from the various security agencies as "a matter of course" and responds accordingly.

The tightening of security at the AIS comes after security at Parliament House was strengthened in response to the increased terrorist threat with federal police officers replacing unarmed public servants.

In late September, ACT Policing encouraged Canberra business owners and members of the public to assess their current security measures amid the heightened terrorist alert.

Territory police chief Rudi Lammers said ACT Policing had been in regular contact with the Australian Federal Police and ACT government to identify any potential threats to infrastructure or large gatherings of people.

"We haven't done anything noticeably different in the community, apart from we're much more alert to the possibility of a terrorist attack," he said.

"The community doesn't need to be concerned, and doesn't need to be startled, but it needs to be continually alert to the possibilities of a government-stated terrorist attack likelihood."

Prime Minister Tony Abbott has stressed raising the terror threat level did not mean an attack was "imminent" but instead that there were people in Australian with the "intent and capability" to carry out a terror attack.

The National Gallery was also contacted for comment.