Two men alleged to have been involved in a plot to bring down a passenger plane are to appear in a Sydney court today.
New South Wales counter-terrorism police have charged a 49-year-old man from Lakemba and a 32-year-old Punchbowl man arrested in raids last weekend across Sydney.
They have each been charged with two counts of preparing for, or planning, a terrorist attack and are due to face court in Parramatta. The maximum penalty for the offence is life imprisonment.
Another man - arrested at Surry Hills - remains in police custody under the "specified time" provisions.
"This legislation recognises that terrorism investigations are complex and there can be legitimate reasons for extended periods of detention for suspects in such matters," the Australian Federal Police said in a statement.
A 50-year-old man was released from police custody on Tuesday without charge.
All four men were arrested on Saturday in raids across Sydney. Authorities alleged they were involved in a plot to bring down a passenger plane using an improvised device.
The NSW Joint Counter-Terrorism team raided several properties around the city, including in the suburbs of Lakemba, Punchbowl, Surry Hills, Wiley Park and Bankstown.
On Thursday, the threat level for Australian aviation was returned to possible, after being raised to probable last week.
Prime Minister Malcolm Turnbull announced the threat to attack an aircraft last week had been disrupted and contained.
Additional security measures were in place at Sydney Airport and other major airports, causing major delays, however Mr Turnbull said he expected these to be modified within 24 hours.
He said there would still be enhanced security measures at airports but it would be done in a way that caused less delay to the travelling public.
"You should expect to receive advice from airlines within 24 hours that arrival times before a flight will be restored to those that previously applied - but some airlines differ," he warned.
He said the head of the Australian Security Intelligence Organisation (ASIO) had decided to downgrade the aviation threat level.
Meanwhile, Australia's terror threat level, which is also set on the advice of ASIO, remained at probable. The threat level was raised to probable in 2014, and since then 70 people have been charged as a result of 31 counter-terrorism operations around the country.