DUBAI (Reuters) - A Bahraini court on Sunday ordered life sentences for three senior opposition members, overturning a previous acquittal on charges of spying for Qatar in what an international rights group called a “travesty of justice”.

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A statement from the public prosecutor said the court sentenced Sheikh Ali Salman, secretary-general of the opposition al-Wefaq group, and Sheikh Hassan Sultan and Ali Alaswad, members of the same group, to life in jail for transferring confidential information and receiving financial support from Qatar.

Bahrain’s public prosecutor had appealed against a court ruling that acquitted the three senior leaders last June in a rare win for opposition figures who say they have been targeted by prosecutors for their political views.

Sultan and Alaswad were tried in absentia. Salman is already serving a four-year prison sentence for inciting hatred and insulting the interior ministry, after he was arrested in 2015.

Along with Saudi Arabia, the United Arab Emirates and Egypt, Bahrain imposed a boycott on Qatar last year, accusing it of supporting terrorism and cosying up to Iran.

Qatar denies the charges, saying they are an attempt to undermine its sovereignty.

Since the Bahrain authorities crushed street protests in 2011, demonstrators have clashed frequently with security forces, who have been targeted by several bomb attacks. Manama says Qatar supports the unrest, accusations denied by Doha.

“This verdict is a travesty of justice that demonstrates the Bahraini authorities’ relentless and unlawful efforts to silence any form of dissent,” Amnesty International said in a statement.

“Sheikh Ali Salman is a prisoner of conscience who is being held solely for peacefully exercising his right to freedom of expression.”

Wefaq, which has strong links to the country’s Shi’ite Muslim majority, has campaigned for social and political reforms in the country, which is ruled by a Sunni Muslim royal family.

Majority-Shi’ite Iran criticized the verdicts, its state news agency IRNA said.

“These verdicts leave no doubt for public opinion and the international community that Bahrain is not looking for reform but has decided to intensify the repression,” IRNA quoted Foreign Ministry spokesman Bahram Qasemi as saying.

Bahrain has frequently accused Iran of interference in its internal affairs. Tehran denies the accusation.

Alaswad, who has lived in London since 2011, has told Reuters that the public prosecutor used secret witnesses and a video from a Bahraini television channel which experts described as edited and incomplete.