Puigdemont, who was set to appear in a German court following his arrest Sunday under a European warrant issued by Spain, filed a petition with the UN Human Rights Committee earlier this month.
His lawyer, British national Ben Emmerson who is himself a former UN rights expert, told reporters in Brussels on March 2nd that he had filed a case with the committee.
- Puigdemont to face court in Germany after arrest at Danish border
- WATCH: Angry protest in Barcelona after ex-Catalan leader arrested
He said the filing accused Madrid of violating Puigdemont's right to be freely elected and his rights to freedom of association and expression.
On Monday, UN rights office spokeswoman Julia Gronnevet confirmed "the registration of the communication," but said she could not provide more details since the case was "confidential".
She did say however that "the next step in this process is that the State Party (Spain) has six months to respond."
The Geneva-based committee, made up of 18 independent experts, is tasked with monitoring countries' compliance and implementation of the International Covenant on Civil and Political Rights.
Puigdemont's arrest on Sunday came five months after he went on the run as Spanish prosecutors sought to charge him with sedition and rebellion after a vote by the Catalan parliament to declare independence.
It marks the latest chapter in a secession saga that has bitterly divided Catalans and triggered Spain's worst political crisis in decades.