Two men have been arrested in Sydney following a police crackdown on terrorist activity.

Police said the arrests were timely and foiled terror plans against government targets, but said no specific targets or time frame were planned for the activities.

Related to September's counter-terrorism raids, the latest raids follow a comment by Australia's prime minister Tony Abbott that there was a heightened "terror chatter" among terrorist sympathisers since the recent cafe siege.

According to police, one of the men arrested had documents that mentioned potential government targets, the BBC reported.

Police had said in September that they had foiled a plot to "commit violent acts" in Australia, including a plan to behead a member of the public.

A possible Mumbai-style attack against the Australian Parliament and its prime minister was aborted by the police raids.

The raids have targeted sympathisers of the Islamic State, accused of helping people travel overseas to fight with extremists.

Tensions have been heightened after Australia joined the allied attack against IS in the Middle East.