In an unusual show of respect for Thailand's fallen leader, Facebook has opted to block all ads in the country for an undetermined length of time.

The social network said the move is in observance of a "cultural custom" as the nation mourns the late Thai King, Bhumibol Adulyadej, who died Thursday at the age of 88.

"Thailand is in a period of mourning due to the death of the King and removal of ads is a cultural custom," a spokesperson wrote to advertisers in a blog post. "We don't yet know the duration of the mourning period. We'll keep you posted of any additional details as they become available."

A funeral for Adulyadej — who was the world's longest-reigning monarch — drew thousands of grieving citizens in the Thai capital of Bangkok on Friday. National media broadcasts went black as his body underwent a traditional bathing ceremony.

As part of his remembrance, many Thai citizens are wearing only dark colors this week, and several websites and television stations have gone completely black-and-white. Monochrome footage of the widely revered leader's life has dominated the airwaves.

Google Thailand dropped its familiar rainbow letters to honor the late king. Image: google, screenshot

The decision to temporarily drop ads seems to be a first for Facebook, which has cultivated a sizable market in the country. The platform boasts an estimated 37 million Thai users — mostly on mobile — who tend to post three times more frequently than the average user worldwide, according to Facebook chief operating officer Sheryl Sandberg.

Perhaps as a result, Facebook ads have proven particularly successful in the country, according to a report in Thai newspaper The Nation.

Research firm Emarketer pegged the yearly Facebook ad spend in Thailand at $81.7 million, meaning that the web giant could be forgoing as much as $6.8 million per month in the blackout — though that estimate is rough.

The company opened its first office in the country last fall as part of an ongoing push to beef up operations in emerging markets.

Part of that effort involves helping brands tailor ads to fit country-specific cultural norms and adjust posts for different bandwidth speeds.

A campaign for Durex condoms in Indonesia, for instance, would load separate videos depending on the viewer's sex. Each was catered to the country's particular attitudes toward gender roles and cultural norms.

“The ability to tell a powerful story can connect people despite geographic, linguistic, technological and even cultural boundaries," Melissa Oppenheim, who heads up the program that handles such considerations, told Mashable in an earlier interview.

In this instance, Facebook's heightened sensitivity toward its users' various cultures means cutting off ads altogether.

The platform's worldwide expansion hasn't been without controversy, however. Facebook faced criticism in India over accusations that its "free basics" service violated net neutrality, and human rights advocates argued that its "safety check" feature, which lets users notify friends and family of their situation in the event of a disaster, was heavily biased toward western countries.

The company has since worked to make the tool's coverage more comprehensive.