The U.S. Department of Justice has charged two former employees of the social media network Twitter with spying on users for Saudi Arabia’s government, The Washington Post reported Wednesday.

The charges were unveiled earlier in the day in San Francisco in a case that will likely raise concerns about U.S. relations with ally Saudi Arabia and the threat of autocrats spying on users via Silicon Valley-based web platforms.

According to the newspaper, ex-Twitter employee Ahmad Abouammo, a U.S. citizen, was arrested Tuesday after allegedly spying on the accounts of three users on behalf of the government in Riyadh.

Another ex-employee, Ali Alzabarah, a Saudi citizen, was accused of accessing personal information of some 6,000 Twitter accounts in 2015, including that of prominent political dissident Omar Abdulaziz, the newspaper reported.

Prosecutors also charged another Saudi citizen, Ahmed Almutairi, with spying, saying he acted as an intermediary between Saudi officials and the rogue Twitter workers. Alzabarah and Almutairi are understood to be in Saudi Arabia.

Prosecutors say the three men were working in coordination with a Saudi official who leads a charitable organization belonging to Saudi Arabia’s powerful crown prince and de facto ruler Mohammad bin Salman, who is better known as MBS.

While the name of this individual was not disclosed in the indictment, which was published by The Washington Post, the newspaper identified him as Bader Al Asaker, who runs the charity Misk on behalf of MBS.

Tensions between Riyadh and Washington have run high since October 2018, when a Saudi hit squad killed and dismembered Saudi journalist Jamal Khashoggi, a U.S. resident, Washington Post columnist and critic of MBS, in the Saudi consulate in Istanbul.

U.S. President Donald Trump has since defended maintaining ties with Riyadh, but the CIA reportedly concluded that MBS ordered the Khashoggi hit and U.S. lawmakers have urged the administration to distance itself from the kingdom.