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.

Australian investigators were able to link social media accounts used in the affair to the city of Edmonton in western Canada, its police force 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.

Edmonton police reported that they had arrested a man, Ghazi Shanta, 33, and a woman, Diana Kadri, 32, who are each charged with extortion and conspiracy to commit extortion.

Two men in their 20s were also arrested in Sydney.

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

"With the immediacy of today's communication tools, it was critical for us to collaborate with Australian police to make simultaneous arrests on opposite sides of the planet," Phil Hawkins of the Edmonton force's Cyber Crime Investigations Unit said.

"The search warrants were executed seamlessly, and together, we were able to bring four suspects in two countries into custody without incident," he said.

The unit got involved following an Interpol request from the Australian Federal Police.