"We should not for one minute think this investigation has now reached its conclusion": AFP acting Commissioner Andrew Colvin. Credit:Cameron Spencer As the nation continued to come to grips with allegations of an Islamic State plot to murder Australians on camera, Prime Minister Tony Abbott confirmed that an attack was expected "within days" had authorities not moved when they did. The Prime Minister said police "expect further charges to be laid against other individuals" from among the 15 people arrested in Sydney in the dawn raids on Thursday. "It is a serious situation when all you need to do to carry out a terrorist attack is to have a knife, an iPhone and a victim," Mr Abbott said. AFP acting Commissioner Andrew Colvin told a Friday media conference that "a number of people are still being detained" but refused to say how many.

Intercepted phone call revealed horrific terror plans: Mohammad Ali Baryalei. Under laws introduced by the Howard government after the 2005 London bombings, a person can be held for up to 14 days under a "preventative detention order" if authorities believe "there is a threat of an imminent terrorist attack". This power has never before been used. Extraordinary powers: Police hold three suspects without charge. Credit:NSW Police The powers are due to expire next year because of a "sunset clause" written into the legislation. But under a raft of counter-terrorism laws the Abbott government plans to introduce to federal Parliament next week, the sunset clause would be extended for another 10 years.

Thursday's raids were launched after police intercepted a phone call between Mohammad Ali Baryalei – a top Australian terrorism recruiter currently believed to be in Syria – and Sydney man Omarjan Azari in which they allegedly discussed plans to snatch a member of the public off a Sydney street and kill them in front of a camera. The video would then be sent to the Islamic State group's powerful propaganda wing to post online. Azari, 22, has been charged with conspiring to plan or prepare a terrorist act, which police allege was intended to "shock, horrify and terrify the community". One other man has been charged with firearms offences and released on bail. Mr Colvin stressed that Thursday had been "very much a disruption exercise". "We should not for one minute think that this investigation has now reached its conclusion," he said. "We can expect to see more activity … in the coming days, weeks and months." Fairfax Media understands the bulk of the property police seized during the Thursday raids was communications equipment.

"We've seized a hell of a lot of electronic data and that will take a considerable amount of time to work our way through," a counter-terrorism source said. Police are understood to be working on finding evidence that Azari brought other members of the group into the detailed planning of the attacks. Mr Abbott also confirmed that security in Parliament House in Canberra was being stepped up after "chatter" between "Australians in Syria and Iraq and their supporters here in Australia" about a potential attack on the building. The AFP will take over protecting the inside of the building from the usual unarmed security guards. Meanwhile a police source told Fairfax Media there was a link between Azari and Agim Kruezi – who has been arrested in separate raids in Brisbane – drawing the Sydney and Brisbane plots together.

"[Kruezi] did come to Sydney at some stage," the source said. "They knew each other." Police allege that Kruezi previously committed offences related to a rival Islamist group Jabhat al Nusra but then switched his allegiance to the Islamic State. The heightened terrorism alert meanwhile extended to the Australian Defence Force, which announced it was stepping up security on all bases and barracks across the country. In May last year, British off-duty soldier Lee Rigby was run down on a London street and hacked to death in front of horrified bystanders by two Islamic militants. Defence Minister David Johnston told Fairfax Media: "We're always very concerned about the safety of our people. We're constantly surveilling the security of not just our members but their families and I'm confident we have that in hand."

Loading Fairfax Media understands the upgrade means more security guards and generally tighter security procedures. Senator Johnston said Thursday's raids underscored the need for Australian involvement in Iraq. "Clearly there is a nexus between the success that ISIL has had in seizing a very large slice of the Levant and that's one of the motivations behind what we need to do to degrade, disrupt and destroy them."