SYDNEY (AFP) - Two alleged members of international hacker group Anonymous were charged by Australian authorities on Thursday with targeting local and Indonesian government websites.

The Australian Federal Police said the men, aged 18 and 40, knew each other online and "targeted organisations including a large Internet service provider and web servers" hosting the government sites.

"It is not harmless fun," the federal police national manager for high-tech crime operations Tim Morris said of the alleged attacks.

"The impairment or disruption of communications to or from computer networks is a criminal act and can have serious consequences."

Activist group Anonymous is believed to be a loosely affiliated hacker collective that conducts online attacks internationally.

In 2012, it claimed responsibility for briefly shutting down a computer server belonging to Australia's domestic spy agency ASIO.

One of the men was charged with aiding the unauthorised modification of a computer network to cause impairment, and the unauthorised modification of Indonesian government web servers to cause impairment.

The other was charged with the unauthorised modification of an Internet service provider to cause impairment, and the unauthorised access to and modification of restricted data on a state government website.

Both men were due to face court later Thursday.