Fifteen people have been detained and one person charged with terrorism offences following pre-dawn raids across Sydney and Brisbane.

Fifteen people have been detained and one person charged with terrorism offences, following pre-dawn raids across Sydney and Brisbane.

Authorities on Thursday confirmed at least one person had been charged and would face court in Sydney later in the day following the largest counter-terrorism in the nation’s history.

More than 800 counter-terrorism police and ASIO officers swooped on homes in the early hours, with some of those detained believed to have links to the terror group Islamic State.

In Sydney alone, 25 arrest warrants were executed.

The joint operation comes less than a week after Australia’s terror alert level was raised from medium to high.

Australian Federal Police acting commissioner Andrew Colvin said the operation which resulted in Thursday’s raids began earlier this year.

“Police believe this group … have the intention and have started to carry out planning to commit violent acts here in Australia,” he said.

“Those violent acts particularly related to random acts against members of the public.”

He said the operation was about police disrupting the potential for violence.

Mr Colvin said that three raids in the southeast Queensland suburbs of Logan, Underwood and Mount Gravatt East on Thursday morning were linked to similar raids in the area last week.

“The warrants that you saw today are a follow up from that investigation, or a continuation of that investigation,” he said.

He said 70 officers were involved in the Brisbane raids.

Mr Colvin said officers were also investigating links between last week’s Queensland raids and those in Sydney on Thursday.

Counter-terrorism officers last week raided several southeast Queensland properties, including an Islamic centre at Underwood, south of Brisbane.

Brisbane man Omar Succarieh, 31, was charged with terrorism-related offences and is due to apply for bail in court on Thursday.

Succarieh stands 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.

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

Succarieh is believed to be the brother of Ahmed Succarieh, who reportedly became Australia’s first suicide bomber in Syria last year.

Mr Colvin said the inter-state operation showed police were well co-ordinated across the country.

“While the raids in Queensland are not directly related to what’s happened here today in NSW, the investigations continue, and we are looking at linkages between the two,” Mr Colvin said.

“The police organisations in this country work very closely through our linked-up national counter-terrorism co-ordination arrangements, and you’ve seen that working very effectively today.”

Some of those taken into custody had already had their passports cancelled.

NSW police commissioner Andrew Scipione said “reasonable force” was used to detain one man.

“Today’s operation reflects the reality of the threat that we actually face,” he said.

Mr Scipione said random attacks were planned.

“All of those plans that may have been on foot are thwarted,” he said.

Homes were raided in at least 12 suburbs in the city’s north-west including Beecroft, Bella Vista, Guildford, Merrylands, Northmead, Wentworthville, Marsfield, Westmead, Castle Hill, Revesby, Bass Hill and Regents Park.

The arrests in Sydney follow months of surveillance of people linked to the terrorist group Islamic State, which has been cutting a barbaric path through Iraq and Syria.

Sydney’s Operation Appleby comes less than a week after outgoing spy chief David Irvine raised the terror alert level from medium to high amid growing fears about the prospect of terror attack on home soil.

Mr Scipione said more details would emerge later on Thursday after the man who had been arrested faced Central Local Court in Sydney.