WA police on alert for terrorism threats

The AFL finals match in Perth this weekend will have a stronger police presence now Australia's terrorism alert level has been raised from medium to high.

The alert shift announced by Prime Minister Tony Abbott on Friday means a terrorist attack is considered "likely", although he stressed it did not mean an attack was imminent.

WA Police Acting Commissioner Steve Brown told reporters there would be a slightly stronger police presence on Saturday at the Patersons Stadium match between the Fremantle Dockers and Port Adelaide.

"We have no specific threat in regards to the football," he said.

"If you've got a ticket, go to the football."

Mr Brown insisted people should continue with their daily lives as normal, including attending events and using public transport.

"You should not avoid nor change your daily life. The train system is safe, the transport system is safe, Western Australia is safe," he said.

"Be alert, be aware, report what you see to the agencies and we will deal with it."

Mr Brown said anyone going through security at the airport or going to the football should be patient and arrive a bit earlier.

He said police would also increase their presence at future politically motivated gatherings, but said he was not concerned about police resources being stretched.

Premier Colin Barnett said he had been briefed by the prime minister's office over the past few days and said people should not be alarmed.

"All security arrangements are being checked to make sure everything is in place but yes, there is a danger," he told reporters.

"There are a number of people in Australia who are now radicalised and they are capable of carrying out some terrorist act."

He said all relevant agencies were working to minimise the risk.