Image copyright EPA Image caption Police conducted sweeping anti-terror raids in Sydney on Thursday

Security is being upgraded at the Australian parliament following "chatter" suggesting extremists could target it for attack.

PM Tony Abbot said Australian Federal Police would assume responsibility for security at the site in Canberra.

The move came a day after major anti-terrorism raids took place in Sydney.

They were aimed at thwarting an alleged plan by Islamic State (IS) supporters to carry out killings in Australia, including an on-camera beheading.

In recent weeks, IS - a militant Islamist movement which has seized vast areas of Iraq and Syria - has released video footage showing the beheadings of two American journalists and a British aid worker seized.

'Unusual level of fanaticism'

Speaking to the Australian Broadcasting Corporation, Mr Abbott said parliament had been identified as a potential target.

"There certainly has been chatter amongst the terrorist support networks of an attack on government and government people, and Parliament House has been specifically mentioned," he said.

As a result, an urgent security review had taken place.

"Subsequently we are placing the Australian Federal Police in charge of security, not just outside the building but inside the building as well," he said.

Security has until now been handled by an in-house security team.

Asked about Thursday's raids, Mr Abbott said that security officials had acted quickly to disrupt the alleged terror network "because we believed that a demonstration execution was likely quickly".

More than 800 officers took part in the operation, which resulted in 15 arrests.

Image copyright New South Wales Police Image caption Thursday's raids have been described as Australia's biggest anti-terrorism operation

Image copyright EPA Image caption Mr Abbott said security officials had to act quickly in response to intelligence received

Australia media reports say the operation was triggered by an intercepted telephone call between the most senior Australian member of IS and domestic sympathisers in which he told them to carry out a series of random beheadings.

Two men have since been charged. One of them, 22-year-old Omarjan Azari, has been charged with conspiracy to commit acts in preparation of a terrorist act and financing terrorism, the AFP said in a statement.

Prosecutor Michael Allnutt said Mr Azari had planned to commit "extremely serious" offences that involved "an unusual level of fanaticism" and were "clearly designed to shock, horrify and terrify" the public.

A 24-year-old man was charged with unauthorised possession of a prohibited weapon and possessing ammunition without a licence.

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Australia last week raised its terror threat level from medium to high - the second highest rank - amid mounting concern over the impact of Australians fighting with Islamic militant groups in the Middle East on domestic security.

Officials say dozens of Australians have gone to fight for IS, which has taken control of large swathes of Iraq and Syria, and the al-Nusra Front, an al-Qaeda-affiliated rebel group in Syria.

Australia has recently committed troops to combat IS in Iraq.