Seventeen Filipina workers in Saudi Arabia have been detained after they took part in a Halloween party, the Philippines foreign ministry says.
The women were taken into custody on Friday by intelligence officers who raided a compound in Riyadh, after neighbours complained about the noise.
It is not yet clear what charges they are facing.
But the foreign ministry noted that Saudi laws prohibit unattached men and women being seen together in public.
The Philippine ambassador in Riyadh, Adnan Alonto, told the ministry that initial information indicated the organisers of the party had been charged with holding an event without a permit and for disturbing the neighbourhood.
The Philippine Star newspaper cited a Facebook post by a man called Humoud Al Fajrawi as saying that some of the partygoers had not known that the event was Halloween-themed.
On Sunday, Mr Alonto issued an advisory reminding the Filipino community in Saudi Arabia to "refrain from organising or attending events or gatherings that are unsanctioned or without permission" from the local authorities.
"In addition, everyone is reminded to avoid mixed crowds, consuming liquor, and holding public practice of traditions that are associated with religions other than Islam, such as Halloween, Valentines and Christmas."
Saudi Arabia does not tolerate public worship by adherents of religions other than Islam.
In its 2018 report, the US Commission on International Religious Freedom said Saudi religious police officers had in recent years "raided private non-Muslim religious gatherings organized by expatriate workers and arrested or deported participants, especially when the gatherings were loud or involved large numbers of people or symbols visible from outside the building".
However, it noted that since 2016 the powers of the religious police has been sharply curtailed by royal decree and both Muslims and non-Muslims had reported decreased harassment and raids.
Expatriate workers from Africa and South-East Asia have also been detained by religious police on the charges of using witchcraft against their employers, disrupting Saudi society by dividing families, or distorting religious texts, according to the commission.
The UN estimates that expatriate residents make up as much as 37% of the Saudi population. Although exact numbers are not available, at least two million of the expatriates are non-Muslims.