GENEVA (Reuters) - The U.N. Human Rights Office said on Friday there were “serious doubts” whether three Bahraini opposition leaders were given a fair trial after Bahrain’s highest court upheld this week their life sentences on charges of spying for Qatar.

Sheikh Ali Salman, leader of the now banned Shi’ite Muslim opposition group al-Wefaq and senior members Sheikh Hassan Sultan and Ali Alaswad were sentenced to life imprisonment in November, overturning a previous acquittal.

Al-Wefaq played a leading role in a 2011 uprising against Bahrain’s Sunni rulers, whom the Shi’ite majority accuse of discrimination and human rights abuses. Bahrain denies this. It has since banned al Wefaq and most of the group’s leadership has been imprisoned or left the country.

“We are deeply concerned that these convictions are due to their opposition to the Bahraini Government and its policies,” said office spokeswoman Marta Hurtado in an e-mailed comment.

“There are also serious doubts concerning whether the court proceedings respected the right to a fair trial.”

Salman is already serving a four-year prison sentence for inciting hatred and insulting the interior ministry following his arrest in 2015. The two other men were tried in absentia.

Bahrain is among the Arab countries imposing a diplomatic, trade and transport boycott on Qatar since June 2017 over allegations it supports terrorism, a charge Doha denies. The other countries are Saudi Arabia, the United Arab Emirates and Egypt.