Police in Australia have raided properties in several Sydney suburbs and arrested four men suspected of plotting a terrorist attack.
Prime Minister Malcolm Turnbull said the counter-terrorism raids were designed to stop "terrorist attacks in Australia".
Fairfax Media, News Corp and the Australian Broadcasting Corporation reported that the raids were related to a bomb plot involving aircraft.
The operation was carried out by the Australian Federal Police, New South Wales state police and the Australian Security Intelligence Organisation, the country's domestic spy agency.
Seven Network television reported that 40 riot squad officers stormed an inner Sydney house before an explosives team found a suspicious device.