Saudi Arabia’s top government-funded think tank is studying the possible effects on oil markets of a breakup of OPEC, a remarkable research effort for a country that has dominated the oil cartel for nearly 60 years.

The effort coincides with new pressures on the Saudi government, including from the U.S., where President Trump has accused the cartel of pushing up oil prices, and from investors who distanced themselves from the kingdom after the brutal killing of a U.S.-based Saudi journalist.

While the think tank’s president, Adam Sieminski, said the study hadn’t been triggered by Mr. Trump’s statements, a senior adviser familiar with the project said it provided an opportunity to take into account the criticism from Washington. Depending on the findings, the study could offer a defense of the cartel and the Saudi role in it.

The research project doesn’t reflect an active debate inside the government over whether to leave the Organization of the Petroleum Exporting Countries in the near term, according to people familiar with the matter.

Senior Saudi officials see the study as a high priority economic-policy inquiry, according to these people. Mr. Sieminski said he ordered the study, and that the analysis isn’t unusual and explores topics his researchers normally delve into.