Saudi Arabia’s King Salman attends a summit between Arab league and European Union member states, in the Red Sea resort of Sharm el-Sheikh, Egypt, Feb. 24, 2019. Photo: Reuters / Mohamed Abd El Ghany.

Amnesty International has called on Saudi Arabia to reveal the whereabouts of a Qatari father and son who allegedly disappeared during a visit to the kingdom last month, the rights group said in a letter published on Tuesday.

Qatar’s state-linked National Human Rights Committee (NHRC) said in August that 70-year-old Ali Nasser Ali Jarallah and his son Abdulhadi Ali Nasser Ali, 17, were “forcibly disappeared” in the Eastern Province of Saudi Arabia after entering on a family visit permit.

In the letter addressed to Saudi King Salman, Amnesty International said if the two men were detained, then Riyadh should disclose the reason and release them unless “they are promptly charged with a recognizable criminal offense.”

Saudi Arabia’s government communications office did not immediately respond to a Reuters request for comment. The NHRC said it had no update on the fate of the men.

The two Gulf states are locked in a bitter dispute that saw Saudi Arabia, along with the United Arab Emirates, Bahrain and Egypt, cut all ties with Qatar in mid-2017 over allegations it supports terrorism, a charge Doha denies.

Qataris have since been barred from entering the kingdom, with which Qatar shares its only land border, beyond exceptional circumstances such as family visitation.

The two men were en route to see a relative in the eastern city of Dammam and last contacted their family on Aug. 18, according to Amnesty.

It called on Saudi authorities to ensure Jarallah has access to medical care, saying he suffered from diabetes, heart and kidney-related conditions.

Saudi Arabia in July released a Qatari national who was arrested in Yemen on suspicion of working with the Iran-aligned Houthi movement, which a Saudi-led military coalition has been battling for over four years.

Another Qatari national, Abdulaziz Saeed Abdulla, has been detained in the kingdom since July 2018, according to the NHRC.