By Andrew Brown in Canberra

Security at Parliament House has been bolstered after pro-Palestinian protesters scaled the roof of the building during a demonstration.

Four people were arrested on July 4 after climbing onto the roof of Parliament House and unfurling banners, which triggered an investigation into security procedures in the building.

House of Representatives Speaker Milton Dick confirmed short-term security measures had been increased following the incident.

“Measures include physical, procedural and intelligence based enhancements,” he told parliament on Monday.

“For security reasons, I will not detail the specific measures that have been implemented, however, these enhancements have occurred and are ongoing.”

Mr Dick said longer-term security upgrades were being considered following talks with security agencies.

The move coincides with a threat by Australian Federal Police to walk off the job in a move that would likely shut down the federal parliament.

Officers would leave their posts at Parliament House for the first time, to strike over what the union describes as a “toxic” pay deal.

Politicians and political events would not be guarded by the AFP unless there was a “significant” threat, the union said on Monday.

The Speaker said the upgrade to security also took into consideration the upgrade to Australia’s terror threat level.

ASIO increased the threat level last week from possible to probable, the first time in 10 years the warning had risen.

Mr Dick said security issues around Parliament House needed to be taken seriously.

“The security and access to Australian Parliament House must always be balanced to keep democracy open to the people, whilst also protecting those who visit and work in the building and surrounds,” he said.

“Australian Parliament House is a key pillar of our democracy. It is also a source of national pride.”

AFP union threatens to ‘disrupt parliament’ over pay