The leaders of a Bahraini uprising last spring were in "intelligence contact" with Iran and its Lebanese ally Hezbollah, a public prosecution official told a news conference after 20 of the organizers' sentences were upheld by a court on Tuesday,
"It is established clearly to us from this verdict that some of the accused had relations and strived to have relations and intelligence contacts with a foreign organization, which is Hezbollah, which works in the interests of Iran," Wael Boualai told a news conference, in comments carried by state media.
Six of the 20 men whose jail terms – some of them life sentences – were upheld were found guilty of "intelligence contacts with foreign bodies". They were also jailed for offenses including trying to overturn the system of government and violating the constitution. The 20 deny all charges against them, saying they wanted only democratic reform.
The Bahraini civilian court's decision to uphold the sentences could dim prospects for defusing persistent unrest and advancing reform in the important U.S. ally against Iran.
Bahrain, where the U.S. Fifth Fleet is based, has been in political turmoil since a protest movement dominated by majority Shi'ite Muslims erupted in February 2011 during a wave of revolts against authoritarian governments across the Arab world.
The Sunni Muslim ruling Al Khalifa family put down the uprising with martial law and the aid of troops from Gulf neighbors Saudi Arabia and the United Arab Emirates, but unrest later resumed with daily clashes between Shi'ites and police. 
"All the accused are guilty in the case of taking part in a conspiracy to overturn the system of government, contacts with foreign bodies and violation the constitution," the state news agency BNA said, referring to them as a "terrorist group".
The verdicts, originally issued by a military court against 21 men, including seven in absentia, comprise eight life sentences. Thirteen remain in jail after one was released. Defense lawyers said Tuesday's ruling could be appealed.
Opposition activists fear Bahraini authorities want to prolong the case and hold on to the men as bargaining chips in an eventual resolution to the conflict. The government says courts in the Gulf monarchy are independent.
The authorities have initiated low-level talks with opposition groups, but said they must do more to stop street violence. The opposition says this stance is a ruse to avoid concessions and they are not responsible for clashes.
The 20 men have become popular heroes whose release could reinvigorate the protest movement and demands for parliamentary powers to legislate and form governments. Bahraini Shi'ites say they face discrimination, a charge the government denies.
Jane Kinninmont, a Chatham House analyst based in London, said the verdict sent a tough message to protesters as well as Western countries who have tried to persuade Manama to compromise with the protest movement.
"The authorities may be trying to show their strength ahead of a planned dialogue with political societies," she said, adding that could backfire if protests and clashes escalate.
"This may also send a message to the international community about the limits of pressure. Strong Saudi backing for Bahrain has made it less interested in what the West has to say."
Though U.S. officials are keen for a release of Bahraini prisoners to help restore calm, Washington has avoided irritating Manama by calling publicly for their release.
The presence of U.S. warships helps ensure a free flow of oil exports out of the Gulf, which Iran has threatened to blockade if the stand-off with Western powers over its nuclear energy program deteriorates into confrontation.
Danish Foreign Minister Villy Sovndal said the verdict was disappointing and called for the release of Abdulhadi al-Khawaja, a rights activist in the case with Danish nationality.
"It is important that the international community continue to make Bahrain aware of the importance of the country respecting basic human rights," Sovndal said in a written comment.
MILITARY TRIALS 
Eight of the 20 men received life sentences in a military court last year, including al-Khawaja and opposition leader Hassan Mushaimaa, who supported making Bahrain a republic.
Ibrahim Sharif, leader of the opposition Waad party and the only Sunni among the 20, is serving a five-year sentence while blogger Ali Abdulemam was given a 15-year term and is in hiding.
"I am very disappointed. This was a shock to people," said Hussein Jawad, son of Mohammed Jawad, who is serving a 15-year sentence. "If they don't want life or a future for Bahrain, they will keep the verdicts like this."
The 13 in jail refused to turn up at the session in protest over previous closed hearings during which they presented evidence and said they were abused in detention last year to force confessions at the military trial, lawyer Mohammed al-Jishi said.
Sunnis, who fear the rise of Shi'ite Islamists if the government compromises with opposition demands for political reform, praised the ruling. "God is great! God is great!" wrote cleric Mohammed Khalid on Twitter.
U.S.-based rights group Human Rights First said Bahrain's government had missed the chance for a "transitional moment" for reconciliation in a country polarized more than ever.
"The decision to uphold the sentences against the 13 shows the regime has little intention to reform or respond to calls for progress on human rights," said Brian Dooley, director of the group's Human Rights Defenders program.