Jordanian authorities have arrested more than thirty Jordanians working on its territory, and are in al-Ha'ir prisons in Riyadh, Dhahban in Jeddah and a third unknown prison.
They said the arrests began in February and were part of a campaign targeting sympathizers of the Palestinian cause.
So far, the detainees have not been brought to justice, and the Jordanian Engineers Association is looking silently for the fate of three of its members in Saudi prisons.
A Jordanian citizen told Al-Jazeera that he feared his brother, who has been detained for months in a Saudi prison. He says he has been working in Saudi Arabia for years and lives with his wife and children.
According to information from relatives of detainees and those familiar with the file, Riyadh is holding more than thirty Jordanians, and their families say that some form of torture is practiced against them.
According to sources speaking to Al-Jazeera, there is an unspoken charge of supporting and resisting the Palestinian cause.
The arrests follow a decision by Saudi Arabia's Crown Prince Mohammed bin Salman's State Security Service, which involved dozens of Palestinians supporting Hamas.
At the Jordanian Ministry of Foreign Affairs, contacts with the Saudi side do not cease, and the Ministry seeks to hire lawyers for its nationals.
Jordanian sources talk of official dissatisfaction with the continued arrests, and see attempts to twist the arm of Amman, according to observers, Jordanian-Saudi relations are not at their best.
Based on what is said openly and secretly in Jordan, Saudi Arabia's arrest of Jordanian nationals is only one episode of Riyadh's pressure on Amman, a pressure that reflects a soured relationship between the two sides.