Saudi Arabian authorities plan to punish so-called "tourism marriages" under which many older Saudi men are marrying under-aged Yemeni girls and then seeking legal status for their wives in the kingdom, a growing exploitative practice since the ongoing conflict in the neighbouring country.

According to Al Jazeera, the Saudi interior ministry on 6 August said in a statement: "Due to the serious consequences resulting from this issue [Saudi nationals marrying Yemeni women illegally], [the interior ministry] urges citizens to observe the law, pointing out that anyone who marries a foreign woman without prior permission will be brought before the competent authorities for punishment for dealing with unidentified people."

The ongoing conflict in Yemen has forced thousands of Yemenis and third-country nationals to enter Saudi Arabia. The two neighbours share a 1800km border.

As per the UN refugee agency, around 30,000 Yemenis and 10,000 third-country nationals have fled to Saudi Arabia since the conflict began in the Arab nation's poorest country.

Moreover, in May 2015, the Saudi king issued an order that allowed illegal Yemeni immigrants to receive residency permits, which apparently encouraged the older Saudi men to acquire younger brides, some as young as 12.

"Saudi men in their forties and fifties would marry young women aged as young as 12 in return for money given to her family. The desperation and poverty of Yemeni families in Saudi Arabia could lead to a similar situation there," Al Jazeera quoted a UN development agency official as saying.

Saudi Arabia and Yemen do not have laws on a minimum age for marriage. As per a Human Rights Watch report, approximately 14% of girls in the Arab world's poorest nation were married before the age of 15, and 52% before they turned 18.