Saudi Arabia on Friday began expelling over a thousand Nigerian women on religious pilgrimage to the country because they had arrived without male guardians, the first time it sent back such a large group in enforcement of strict rules governing women.

The government ministry that oversees the Hajj pilgrimage said the 1,100 women had violated a longstanding law by travelling without an immediate male relative, adding that females of all nationalities under the age of 45 must have a male guardian during the Hajj pilgrimage.

"This is a rule that is generally applied to women who have applied for a visa to enter the kingdom," the Hajj ministry said in a statement.

In Saudi Arabia, women are not allowed to travel without a male guardian, such as a father, brother, uncle or husband, or at the very least permission from such a relative. In the past, authorities had allowed women over 45 to perform the annual pilgrimage without the guardians as long as they were in groups with male tour operators and pilgrimage officials.

The annual pilgrimage, which this year comes at the end of October, is a religious duty for Muslims who are supposed to make the trip once in their lives. Many arrive weeks in advance.

The expulsions may set the stage for a diplomatic confrontation.

Nigeria's pilgrimage commission says a bilateral agreement exempts its female nationals from the rule, and the country is sending a delegation to Saudi Arabia to discuss the expulsions. They also say some women have been turned back because they appeared to not have sufficient proof of being married despite being accompanied by their husbands.

The women, who arrived in the city of Jiddah in three groups, were held after landing at the international airport starting Monday. Saudi authorities said they would be allowed to return if they came back with guardians, but did not signal any flexibility or recognize the Nigerian claim of an exemption to the guardianship rules.

"The rules of Hajj have been in place for many years and nothing has emerged that requires us not to abide by them," said Hatem bin Hassan Qadi, deputy Hajj minister. He added that he hoped pilgrimage commissions around the world abide by the requirements of the trip before pilgrims' departure.

Rules limiting the independence of Saudi women are far-reaching in the kingdom. They may not study abroad unless a male guardian approves and accompanies them throughout their studies. Government-run hospitals perform surgery on women only with approval of a male guardian, except in emergencies. If a husband or father is not available, mothers turn to their sons for approval to work or travel.

More than 2 million Muslims descend on Saudi Arabia's Mecca for the pilgrimage, with around 1.5 million of them coming from outside the Gulf region.

Pilgrims often save their entire lives for the trip and Muslim philanthropists donate to enable those who cannot afford it. The Hajj, which lasts five days, costs anywhere between $4,000 upward to more than $25,000 per person.