Five people, including a 15-year-old man, were charged on Thursday in Sydney for "associating to organize a terrorist attack" on a government building.

Fifteen people were arrested in December 2014. in Australia as part of a counterterrorist investigation into the planning of an attack. On Thursday morning, a 20-year-old teenager was arrested in his home and the accused, the police said. Similar charges were filed against three more detained detainees at the age of 21 and 22 years.

The arrests that took place on Thursday were related to the information collected in action in December 2014.

"From documents confiscated in December 2014. in Sydney it is clear that government buildings were to be attacked, "said senior Federal Police officer Michael Phelan.

These arrests are part of the Appleby operation, extensive investigations of people suspected of involvement in planning and conducting terrorist attacks in Australia, traveling to Syria and Iraq, and financing of terrorist organizations.

Canberra is concerned about the potential for attacks by individuals acting under the influence of organizations such as the Islamic State (IS) group, which has occupied much of Syria and Iraq.

Phelan said he could not confirm that five people were charged on an IS warrant Thursday although they were under the influence of jihadists from abroad.

Australia has strengthened the degree of anti-terrorism for more than a year, has passed a new law on security, and has carried out a series of anti-terrorist actions.