Police in Australia say a top Islamic State commander ordered a group of men to build a bomb to be placed on a flight out of Sydney.

Authorities have given more detail about what they describe as "one of the most sophisticated plots ever attempted" in the country.

It's emerged one of the terror suspects planned to smuggle the bomb on to an Etihad flight on July 15th - by planting it in luggage belonging to his brother - who knew nothing about it.

One of them had been in contact with a senior figure in the Islamic State group since April - while it's believed parts of a bomb were smuggled in air cargo from Turkey

The two suspects appeared in a Sydney court earlier today - they'll appear in court again in November.

If convicted, they face a maximum penalty of life in prison.