Dual raids were launched after a string of attacks on a Sydney home and online extortion attempts linked to an address in Canada.

The target was the family of a "very senior politician" who is a dual Australian and Iraqi citizen and "spends almost all of his time in Iraq", Australian police said.

The attacks are believed to have begun in December 2019, when masked and armed assailants broke into a home in western Sydney, assaulting a 16-year-old boy and stealing cash.

Months later, shots were fired at the house while two adults, two teenagers and a child were inside. A window was smashed in a separate incident.

Earlier this month, the front porch was set on fire in the dead of night and a threatening note was left outside.

"Throughout this time, the family received various demands for money and threats to their welfare via social media and letters left at their home," police said.

Australian media named the member of parliament as Ahmed Assadi -- a senior figure in the Hashed al-Shaabi, a powerful state-sponsored paramilitary network formed from mostly-Shiite armed groups.

Police did not confirm the man's identity.

Two men in their twenties were arrested in Sydney and a woman and a man in their thirties were arrested in Edmonton, Canada.