RIYADH, Saudi Arabia -- Saudi Arabia has started expelling 1,100 Nigerian women pilgrims for violating the kingdom's rule prohibiting Muslim women from entering the country without a male guardian.

The government-run el-Eqtisad website quotes an unnamed Saudi official Friday as saying the women were detained after landing at the international airport in Jiddah. On Thursday, 171 were sent back and the rest will be returned to Nigeria.

The report says some of the women have been detained since Monday.

In Saudi Arabia, women must be accompanied by or have permission from a "mahram" -- a male guardian -- in order to travel. But in the past, authorities allowed women to perform the annual hajj pilgrimage in groups with male tour operators.

There was no explanation for why the authorities were now enforcing the rule.