Two people were arrested on Thursday in Sydney during a counter-terrorism operation over a plot targeting a government building. Police gave few details about the arrests, although Sydney's Daily Telegraph said one of those held was 15 years old.

The two were charged with one count each of conspiracy to conduct an act in preparation for a terrorist act. There are three other individuals currently in jail who were also expected to be charged with the same offense, said police.

According to Australian Federal Police Deputy Commissioner for National Security Michael Phelan, it was not a new plot.

"Last December, there were a number of documents seized as related to the search warrants we undertook in Sydney and those documents clearly talked about a plan and there was government buildings named in those plans," he said, adding that one of them was the Australian Federal Police offices.

The arrests were part of Operation Appleby, a continuing investigation into persons suspected of being involved in domestic acts of terrorism.

Australia lifted its terror threat alert to "high" - the country's second-highest alarm level - over a year ago, conducted several counter-terrorism raids since and has introduced new national security laws.

According to officials, six attacks in Australia have been foiled over the past year.

The latest arrests come just days ahead of a memorial to mark the one-year anniversary of an Iranian taking hostages in a 17-hour cafe siege in Sydney. Two hostages were killed.

av/msh (AFP, Reuters)