Several arrests have been made in the secret pre-dawn raids in Sydney but the Courier Mail understands there have been no arrests in Brisbane thus far.

Hundreds of police executed search warrants in Logan, Underwood and Mt Gravatt East along with the Sydney suburbs of Beecroft, Bellavista, Guildford, Merrylands, Northmead, Wentworthville, Marsfield, Westmead, Castle Hill, Revesby, Bass Hill and Regents Park.

The raid is believed to have been mounted following months of surveillance of people linked to the terrorist group Islamic State in Iraq and Syria.

The Courier Mail has learned that an estimated 600 officers from the Australian Federal Police, state counter terrorism units and ASIO launched the pre-emptive strike in the early hours of this morning.

The raids and arrests are believed to have been based on the execution of multiple ASIO and AFP warrants.

It is believed that dozens of suspects have been netted, with links to a Brisbane man who was recently arrested on suspected terrorism related charges.

It is believed that a terrorist network had been planning to carry out a series of attacks in Australia.

Last week, Brisbane man Omar Succarieh, 31, was arrested and charged with terrorism-related offences following a series of raids.

He’s accused of fundraising for Syria-based extremist group Jabhat al-Nusra and helping another man, Agim Kruezi, obtain funds to fight for a terror organisation overseas.

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Succarieh, who is due to apply for bail in court on Thursday, is believed to be the brother of Ahmed Succarieh, who reportedly became Australia’s first suicide bomber in Syria last year.

Logan man Kruezi, 22, has alleged links to the Islamic State group.

The raid follows the lifting of the national security alert level from medium to high last Friday by the outgoing director general of ASIO David Irvine.

It is believed the size of the raid eclipsed that of Operation Pendennis in 2005 when several hundred ASIO, AFP and NSW police arrested 13 men across Melbourne and the Sydney suburb of Bankstown, who had been planning bomb attacks in both capitals.

In Brisbane, a double story house on Creek Road, Mount Gravatt East, was among the properties raided.

One neighbour said he had lived near the family, who he described as “Middle Eastern” for more than 20 years but had rarely communicated with them.

The man said he had only heard dogs barking during the morning raid.

A number of Australian Federal Police officers remain at the address.

It has not yet been confirmed whether any arrests have been made.

An AFP spokesperson said further updates would be provided later on Thursday.

Senior government ministers were unable to shed more light on the raids, but praised the work of authorities.

“I note the security agencies, the Police, ASIO are working hard to ensure that we are safe,” Coalition frontbencher Malcolm Turnbull told ABC radio this morning.

“Our security is the consequence of continued vigilance and hard work on the part of the security agencies.

“There is no cause for being complacent about security.

“There are people, regrettably some of them in our midst, that don’t have the nation’s best interest at heart.”

Speaking ahead of this weekend’s G20 Finance Minister’s meeting in Cairns, Joe Hockey said he had confidence in the security measures in place.

“Everyone needs to make sure that with an increased threat level associated with potential terrorist attacks in Australia we have all the necessary precautions taken for both the G20 here in Cairns and also in Brisbane,” the Treasurer told Sunrise.

“But, I am very confident that all bases are covered.

“We have put a lot of effort into this for a long period of time.”

There are about 60 Australians believed to be fighting in Iraq and Syria with groups such as Islamic State, while another 100 are suspected of providing support from Australia.

Originally published as Hundreds of police in terror raids