A UAE court on Sunday sentenced a blogger and four other democracy activists to prison terms after finding them guilty of charges including insulting the Gulf state's leaders.

The State Security Court handed the blogger, Ahmed Mansoor, a three-year prison sentence and the four others each received two years. They have no recourse to appeal.

It also ordered the shutting down of the Hiwar (dialogue) Internet forum used by the activists.

Mansoor had been arrested in April along with Nasser bin Gaith, who lectures at the Abu Dhabi branch of the Sorbonne University, and activists Fahid Salim Dalk, Hassan Ali Khamis and Ahmed Abdul Khaleq.

They were accused of using the Internet to insult leaders of the United Arab Emirates, calling for a boycott of September's Federal National Council elections and for anti-government demonstrations.

Their trial had been criticised as "grossly unfair" by a coalition of seven rights watchdogs including Amnesty International and Human Rights Watch earlier this month.

In a joint statement, the rights groups had called for "all five to be released immediately and unconditionally."

But the Federal Supreme Court, acting in its role as a special security court, pressed ahead announcing its verdict.

The five defendants had refused to show up in court, saying in a message delivered by a police officer that the court "did not enable them to defend themselves."

The defendants are said to be still on a hunger strike which they began earlier this month.

"This is a horrible decision. A complete miscarriage of justice," said Human Rights Watch representative Samer Muscati, who attended the trial.

"This shows that in the UAE you are not guaranteed a fair trial," he added, charging that the trial was "flawed from day one," and pointing out that lawyers "couldn't cross-examine witnesses."

He also criticised the verdict as harsh, pointing out that previous cases in which people were charged based on Article 176 of the UAE's penal code were dealt with as misdemeanours, not at a security court.

Outside the court, Khalifa al-Nuaimi, a relative of bin Ghaith, said the verdict was "shocking and harsh".

"We expected a verdict of not guilty, based on the evidence presented," he said, claiming that only one of seven witnesses brought in by the prosecution linked the defendants to statements made on the Internet.

He expressed hope that the five would be pardoned, which he said many people hoped for.

"We call upon our sheikhs to pardon them. They are their children," he said.