Police said they arrested a man armed with a knife after he attempted to toss a burning package over the fence of the Australian prime minister's Sydney residence on Thursday.

Prime Minister John Howard (search) is on vacation and was not in the residence, close to the shore of Sydney Harbor (search).

The attacker suffered burns but no one else was injured in the incident, which was not believed to be terrorism-related. However, it came amid heightened security concerns following the string of deadly attacks on London's transit system.

The package did not clear the prime minister's fence, police said in a statement.

"The man then allegedly threatened officers from the Australian Protective Services with a knife," it said. "They were able to disarm the man and hold him until North Sydney police arrived."

The man, aged 27, was taken by ambulance to a nearby hospital where he remained under police guard, police said. There was no word on whether he had been charged with any offense.