The UN's religious freedom monitor on Thursday urged Sunni-ruled Bahrain to halt discrimination against its Shiite majority and its spiritual leader, who was expelled from the Gulf kingdom this week.
The case of Sheikh Hussein al-Najati was a stark illustration of the broader mistreatment of Shiites in Bahrain, UN expert Heiner Bielefeldt said in a statement.
He said that he had contacted Bahrain's government to press his "grave concerns" over what he said appeared to be "religiously motivated discrimination" against Najati.
"Targeting the most senior and influential Shia religious figure in Bahrain may amount to intimidating and thus discriminating against the entire Shia Muslim community in the country because of its religious beliefs," he said.
"Discrimination on the grounds of religion or belief constitutes a violation of human rights and fundamental freedoms," he added.
Najati, the Bahrain representative of Iraq-based Shia leader Grand Ayatollah Ali al-Sistani, was among 31 Bahrainis stripped of their citizenship in November 2012 over accusations that they had undermined state security, more than a year after authorities crushed a Shiite uprising in March 2011.
"International law, in particular the Universal Declaration of Human Rights, prohibits arbitrary deprivation of nationality, including on religious grounds," said Bielefeldt, the former head of Germany's national human rights office who took up his UN post in 2010.
Bahrain's interior ministry this week accused Najati -- born in 1960 to Iranian parents in Bahrain -- of collecting and distributing funds in the name of Sistani despite not being an official representative of a party.
The deported cleric arrived in Lebanon on Wednesday.
"I understand that Mr. Najati has consistently refrained from engaging into politics, and has maintained his position and activities strictly in the realm of his religion," said Bielefeldt.
"He is not known to have advocated violence or its use, or to have committed acts that would undermine national security or public order, nor has he been charged or sentenced for committing such acts," he said.
Sistani, who is based in the Iraqi city of Najaf, in 2011 condemned Bahrain's crackdown on Arab Spring-inspired protests which demanded democratic reforms in the Gulf kingdom.
Bahrain remains deeply divided three years after the February 2011 uprising, with persistent protests sparking clashes with police, scores of Shiites jailed on "terror" charges and reconciliation talks deadlocked.