An electrician has been arrested during an anti-terror raid on a semi-rural NSW property after he allegedly sought to assist ISIS overseas on how to "develop and detect missiles".

Authorities allege Haisem Zahab, 42, "researched and designed a laser warning device to help warn against incoming laser-guided munitions used by forces in Syria in Iraq".

They also allege the Australian-born man, who has never travelled to Syria or Iraq, assisted ISIS in designing and modelling systems to develop a long-range guided missile.

There were dramatic scenes outside the court hearing yesterday afternoon, as family of the accused lashed out at the media.

A woman, who masked her face, tried to block the 9NEWS camera from recording her as she walked into court.

Mr Zahab, who was believed to be living with his three children in the small NSW town of Young, was arrested yesterday after more than 20 Australian Federal Police officers swarmed his property.

Neighbours said they heard an "explosion" and commotion when he was arrested.

Mr Zahab, who sat silently in court, did not apply for bail and has been remanded in custody.

Authorities allege Mr Zahab, who worked at a local business installing solar panels, sought to advise ISIS on how to develop "high-tech weapons capability".

At least 20 AFP officers are currently combing the rural property. (9NEWS)

Police will allege Mr Zahab advised ISIS on how to detect and develop missiles. (9NEWS)

They allege Mr Zahab carried out "credible" research for ISIS.

Justice Minister Michael Keenan said the arrest was the result of an 18-month police investigation.

"It reminds us that whether you are in a capital city planning an attack on home soil or whether you are in a small country town trying to assist the terrorist state in the Middle East, you will get caught," Mr Keenan said.

He has been charged with two counts of preparations for incursions into foreign countries for purpose of engaging in hostile activities, which carries a maximum penalty of life in prison.

Prime Minister Malcolm Turnbull said Mr Zahab was not planning any domestic attack.

"This highlights that terrorism, support for terrorist groups, and Islamist extremism is not limited to our major cities," Mr Turnbull said.

"They want to divide us, they want us to turn on each other - we will not let them succeed," he said.

Mr Turnbull said security and police agencies had once again done their job but those authorities relied upon good intelligence from the community.

Officers remain at the property and are combing the area with metal detectors.