DUBAI (Reuters) - A court in the United Arab Emirates upheld on Monday a 10-year jail sentence against pro-democracy campaigner Ahmed Mansoor for criticizing the government on social media, two sources said on Monday.

The state security court’s ruling against Mansoor, who prior to his imprisonment had been one of a tiny number of publicly active rights campaigners in the UAE, was later reported by the Abu Dhabi-government owned National newspaper.

A trade and tourism hub, the UAE is an absolute monarchy which tolerates little public criticism. Mansoor, a 49-year-old electrical engineer and poet, was among five activists convicted of insulting the UAE’s rulers in 2011. They were pardoned the same year.

He was arrested again in March 2017 at his home in Ajman, on charges of publishing false information and rumors, promoting a sectarian and hate-incited agenda, and using social media to “harm national unity and social harmony and damage the country’s reputation”.

In May 2018, he was sentenced to 10 years in prison and handed a fine of 1 million dirhams ($270,000).

The court upheld both the jail sentence and fine on Monday, the two sources said on condition of anonymity.

The National also said that Mansoor would remain under surveillance for three years upon his release and that Monday’s ruling was not subject to further appeal.

United Nations human rights experts, the European Parliament and rights groups such as Amnesty International and Human Rights Watch (HRW), are among those to have urged the UAE to release Mansoor and condemned his detention as a violation of freedom of expression and opinion.

In 2015 Mansoor received the Martin Ennals Award for Human Rights Defenders, an annual prize awarded by a panel of international human rights NGOs, for his work documenting the human rights situation in the UAE.

Amnesty International’s Middle East Research Director, Lynn Maalouf said: “Instead of punishing Ahmed Mansoor for daring to express his opinions, the authorities must ensure his conviction and sentence are quashed and release him immediately and unconditionally.”

Human Rights Watch said in March 2018 it believed Mansoor was being held in solitary confinement, a concern echoed in a resolution by the European Parliament on the case.

“The UAE’s railroading of prominent human rights advocate Ahmed Mansoor is yet another stain on the country’s reputation,” Adam Coogle, Middle East researcher at HRW, said.

“So long as Mansoor remains in prison, no amount of money nor army of public relations firms will be able to wash away this stain.”