Algerian authorities say they arrested 61 Moroccan nationals earlier this month on suspicion of planning "acts of sabotage."
In a statement on Sunday, Morocco's General Directorate of National Security said the suspects were part of "an international Moroccan criminal network."
Those arrested include a former soldier in the Moroccan army. They reportedly entered Algeria via mountain trails from neighbouring Tunisia.
Algeria says they were "preparing to commit acts of sabotage undermining security and public order."
Relations between Algeria and Morocco have been strained for years over the issue of Western Sahara. The United Nations considers the mineral-rich former Spanish colony a non-self-governing territory. But it's been largely controlled by Rabat for almost five decades and Morocco views it as an integral part of its territory.
Algeria supports its pro-independence Polisario Front and its calls for self-determination.
The land border between Algeria and Morocco has been closed since 1994. In 2021, Algiers severed diplomatic relations with Rabat.
In May, the United Nations Security Council adopted a resolution backing Rabat’s autonomy plan for Western Sahara.
The resolution says that genuine autonomy under Moroccan sovereignty could be the “most feasible” solution to the 50-year conflict.