Bahrain's top court has upheld prison sentences against 13 opposition figures charged with plotting to overthrow the Gulf state's minority Sunni rulers in a 2011 uprising.

In a ruling Monday, the Bahraini court rejected appeals from all 13 dissidents, most of whom are majority Shi'ites. Eight of the defendants had been sentenced to life is prison by lower courts, while the other five had received terms of five to 15 years.

The opposition activists were convicted of forming “terrorist” groups to overthrow Bahrain's ruling Al Khalifa family and engaging in “intelligence contacts” with foreign powers — a reference to Shi'ite-majority Iran and Lebanese Shi'ite militant group Hezbollah. Iran denies providing anything more than moral support to Bahraini Shi'ites.

The Bahraini dissidents helped to launch mass anti-government protests in February 2011, demanding democratic reforms and an end to the Sunni monarchy's perceived discrimination against the Shi'ite majority.

Bahrain's main Shi'ite opposition group, Wefaq, responded to the upholding of the dissidents' prison terms by accusing the government of “political persecution.” In messages posted on its Twitter feed, Wefaq said the “revolution continues and the sentences … will energize it.” International rights groups have called on Bahrain to release the opposition figures.

One of those sentenced to life in prison is Abdulhadi al-Khawaja, a rights activist who held a 110-day hunger strike last year to protest his detention. Two other dissidents who received life terms are leaders of the Shi'ite opposition Haq movement — Hassan Mashaima and Abduljalil al-Singace.

In addition to the 13 defendants, the court upheld prison terms for another seven dissidents who were tried in absentia and remain on the run.

Bahrain's 2011 protest movement was inspired by pro-democracy uprisings unfolding in other Arab nations at the time. The Bahraini government crushed the demonstrations in March that year, sending security forces to clear a protest encampment in Manama and bringing in troops from neighboring Sunni-led Gulf states to restore order.

Frequent street battles between Bahraini security forces and Shi'ite demonstrators have continued, mostly outside of Manama. At least 55 people have been killed since the uprising began.