The Australian government on Tuesday said it had received a "credible" terrorism threat linked to Usama bin Laden's Al Qaeda network. It did not say what the threat was.

The message was similar to threats received in recent days by the United States and Britain, Justice Minister Chris Ellison said.

"The Australian government has received credible information as to a possible terrorist threat in Australia over the next couple of months," Ellison told reporters.

"The information, whilst general and not specific as to target and timing is nonetheless credible," Ellison added.

The warning came the day a British-born Muslim convert appeared in a west Australian court and denied charges of plotting to blow up Israeli diplomatic posts in Australia. The warning and the court case were not related.

Australia has been jittery about the possibility of terror attacks since the Oct. 12 bombings on the island of Bali killed nearly 200 people, including about 90 Australians.

Prime Minister John Howard's conservative government has been one of the staunchest supporters of the United States in its war on terror, sending ships, aircraft and elite troops to serve alongside U.S. forces.

On Friday, the FBI warned that Al Qaeda may be planning a "spectacular" terrorist attack intended to damage the U.S. economy and inflict large-scale casualties.

Ellison urged Australians to report anything they considered unusual to police but otherwise to continue their lives as normal.

"Be alert, but not alarmed," he said.

The threat was first received several days ago and then confirmed a couple of days later, he said.

Ellison refused to detail the source of the threat or explain how the government knew it was credible.

Professor Ross Babbage of the Australian National University's strategy and defense program said the warning was expected given a recent audio tape attributed to bin Laden in which the terror mastermind made specific mention of Australia and the Bali bombings.

"Frankly, this latest warning should not really come as a great surprise," Babbage told Sky News. "It is something that we really had to be preparing ourselves for mentally and emotionally for some time."

Federal security agencies were on heightened alert and state and territory governments had been warned of the threat, Ellison said.

"You can rest assured the government is doing everything it can to prevent a terrorist attack in Australia," he added.