A jury on Sunday found Mohammad Shafia, 58, his wife Tooba Yahya, 42, and their son Hamed, 21, from Montreal, guilty of four counts each of first-degree murder for killing Shafia's daughters and his first wife.

"It is difficult to conceive of a more despicable, more heinous, more honourless crime," Judge Robert Maranger said.

He added that their "completely twisted concept of honour" had "absolutely no place in any civilized society."

Geeti, 13, Sahar, 17, Zainab, 19, and Shafia's other wife Rona Amir Mohammad, 52, were found drowned in a car in a canal in Kingston in June 2009.

Prosecutors argued that the sisters had shamed the conservative family with their revealing clothing, refusal to wear hijabs and boyfriends. Rona Amir Mohammad had tried to protect them.

A conviction for first-degree murder carries a mandatory life sentence and at least 25 years must be served before becoming eligible for parole.

The four defendants had maintained their innocence during the 10-week trial despite incriminating wiretap recordings in which Mohammad Shafia said he hoped the devil would defecate on their graves.

Justice Minister Rob Nicholson called honour killings "barbaric and unacceptable in Canada" in a statement issued after the court handed down its verdict.