TONY Abbott has announced the Australian terror threat has been raised from medium to high, meaning an attack is “likely” on home soil.

“Last night the director general of security, ASIO head David Irvine, raised the terror threat to high,” the PM revealed at a press conference in Melbourne.

“Consequently the government today is raising the public alert level to high.”

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The PM stressed “this does not mean that a terror attack is imminent.”

“We have no specific intelligence of a particular plot,” he said.

“What we do have is that there are people with the intent and capability to mount attacks.”

The announcement comes after ASIO’s outgoing chief David Irvine this week revealed security authorities were “actively considering” raising Australia’s terrorism threat level.

For the “vast majority” of Australians the level change will not make any difference to their “daily life”, Mr Abbott said.

But security will be beefed up at airports, ports, military bases and government buildings, in addition to large public events.

media_camera Better safe than sorry ... the raised security alert will result in more security at airports.

The PM said people should be reassured Australia has highly capable police forces who will act with professionalism in these times “as they do in all times”.

A “modest public information campaign” will be released in coming weeks, Mr Abbott said.

But the PM made clear that nothing about “national security threats has anything to do with religion”.

“This is about crime,” he said.

So business as usual for most of us. Makes me wonder why the public level of alert has been raised? — Paul Bongiorno (@PaulBongiorno) September 12, 2014

The Premiers, Chief Ministers and the Opposition Leader were all briefed by the PM ahead of the announcement.

Outgoing spy chief David Irvine said there are about 10,000 foreign fighters in the Middle East — including about 60 to 70 Australians.

Given the rhetoric coming out of the Middle East there is an “increase particularly in intent”, he explained.

media_camera Taking no chances ... outgoing spy chief David Irvine said there are up to 70 Australians fighting in the Middle East.

“I think it is important that we raise awareness partly by raising the threat level and to assure people that the authorities both law enforcement and the security intelligence service are very concerned about this and are watching it with great care.”

Both Mr Abbott and Mr Irvine denied the decision was made in connection to Australia’s support of the US in Iraq.

“Australia has, in fact, been a target of these sorts of groups for a very long time and the decision that I took on the advice of my experts was one that was developed over a period of time,” Mr Irvine said.

We are a tolerant peace loving democracy - we should continue to be that. — Campbell Newman (@theqldpremier) September 12, 2014

Mr Abbott insisted people shouldn’t be afraid to attend events such as the upcoming football finals.

“Normal life in Australia can and must go on,” he said.

Bill Shorten gave Labor’s support to the announcement — declaring the Prime Minister and him were “partners” on national security.

“When it comes to fighting terrorism we are in this together,” the Opposition Leader told reporters in Sydney.

When later asked about possible scepticism, Attorney General George Brandis said there will “always be people in any community who will turn their face against the most obvious evidence in the world”.

“When the Director General of ASIO says that there are 60 Australians fighting with Islamist terrorist organisations in the Middle East he’s not making that up,” the Senator told ABC Radio.

“He’s saying that because that’s what the intelligence tells him.

“There are a few paranoid fantasists in the community who might think that this is a big conspiracy against the Australian people by the national security agencies.

“People who think that are crazy.”

Victorian Premier Denis Napthine described the decision to increase the level as a “prudent and precautionary measure”

“The increase in the alert level is not based on knowledge of a specific attack plan, but rather on a body of evidence that points to an increased likelihood of a terrorist attack in Australia.”

The state’s police chief, Commissioner Ken Lay insisted Victorians should not be “alarmed”.

But he said there will be an increased police presence at tonight’s AFL match at the MCG.

media_camera On alert ... Tony Abbott holds a joint press conference with Attorney-General George Brandis, retiring Director-General of ASIO David Irvine and Acting Commissioner of the Australian Federal Police Andrew Colvin. Picture: Jake Nowakowski

Longer queues at AFL footy finals and at Melbourne airport are some of the impacts that beefed up security will have on Victorians after terror threat levels were raised.

Chief Commissioner Lay said extra security would be put on at major events, but “people should not be alarmed about this”.

“There are no known or specific threats to any Victorians, any Victorian organisation and any Victorian infrastructure or any Victorian event,” he said.”

“We are more than comfortable that we have got the ability to keep Victorians safe.”

Mr Lay said people should leave more time to get in to footy finals and to catch flights, however.

“One of the things that people may see over the next little while is longer queues at thing like the football, perhaps even at the airport and the like,” Mr Lay said.

He urged people and businesses should look out for anything that “doesn’t feel quite right”, including “suspicious property or vehicle rentals”.

“Suspicious purchases in large quantities of fertilisers, chemicals, or other explosives; if people see unusual videoing or photography of diplomatic, consular premises, energy installations, or any other infrastructure,” he said.

Mr Lay said alert levels changed mainly because of “well-documented circumstances where a number of Australians have travelled to Syria to fight with ISIL”.

There are “a number of Victorians” who have arrived home from fighting in Syria, Mr Lay said.

“Their return to Australia creates some obvious risks for the community and Victoria Police,” he said.

In a statement from Greens Leader Christine Milne the party said it accepted the advice of ASIO, “but say we cannot ignore the impact of military engagement in Iraq and the Middle East in increasing the risk at home”.

“We cannot bring Australians together and combat extremism at home by blindly following the USA into yet another Iraq war,” the Senator said.

The terror level has been set at medium on the National Terrorism Public Alert System since the system was introduced in 2003.

The four levels include:

• low — terrorist attack is not expected

• medium — terrorist attack could occur

• high — terrorist attack is likely

• extreme — terrorist attack is imminent or has occurred.

It comes as Australia is set to play a greater role in efforts to fight IS in the Middle East.

Mr Abbott urged members of the public to contact the national security hotline on 1800 1234 00 if they notice anything out of the ordinary or that concerns them.

Originally published as Australia, we’re on ‘high’ terror alert