Three alleged Islamic State supporters have been arrested as one of them planned to carry out attacks on Sydney landmarks.

Police executed a total of six search warrants across Sydney, at Canada Bay, Chester Hill, Greenacre, Green Valley, Ingleburn and Toongabbie.

A 20-year-old and 23-year-old are expected to be charged with being members of the Islamic State terror group.

The younger man, from Greenacre, will also be charged with intending to carry out a terrorist attack on Australian soil.

The NSW Joint Counter Terrorism Team has been monitoring the younger man for the last 12 months after he returned from Lebanon.

It’s alleged he was prepared to travel to Afghanistan to fight for Islamic State.

A 30-year-old associate of the men has also been arrested and will be charged with fraudulently claiming commonwealth benefits.

Image: 9 News