Eleven migrant labourers died of asphyxiation in Saudi Arabia on Wednesday in a fire that engulfed the windowless house they shared, Saudi authorities said.

"Firefighters put out a blaze in an old house lacking windows for ventilation. Eleven people died of asphyxiation, and six others were injured" in the southern province of Najran, the civil defence said in a tweet.

The casualties all hailed from India and Bangladesh, it said.

Nine million foreigners work in the kingdom, many of them from South Asia, according to the last official figures released in 2015.

Rights groups have called on Saudi Arabia and other Arab states to end the widespread kafala - or sponsorship - system, which severely restricts the rights of migrant labourers.

These workers cannot leave the country or switch jobs without written permission from their current employer under kafala, and employers often confiscate their passports and travel documents.