DUBAI, United Arab Emirates (AP) — A U.N. rights expert visiting Saudi Arabia as part of an unprecedented invitation by the government to assess the country's legislation and actions in fighting terrorism said Thursday he was not given access to imprisoned bloggers and activists.

Special Rapporteur Ben Emmerson said he was, however, given rare access to top officials overseeing the country's handling of sensitive terrorism cases, including those of human rights defenders serving sentences under sweeping security legislation. In his preliminary findings , Emmerson expressed concern about reports of the use of torture to extract confession and due process violations by the Specialized Criminal Court, established to try terrorism cases.

Speaking with The Associated Press from Riyadh, Saudi Arabia, Emmerson said: "The picture is extremely mixed."

He said the Saudi government has gone to incredible lengths to humanely rehabilitate Saudis convicted in terrorism cases, while at the same time it has prosecuted and jailed citizens exercising their right to free speech under broadly worded anti-terrorism legislation.

In 2014, Saudi Arabia issued a law that allows the kingdom to prosecute as a terrorist anyone who demands reform, exposes corruption or otherwise engages in dissent by deeming these as acts that could undermine national security.

Emmerson said he made clear during his conversations with Saudi officials that the kingdom's current definition of terrorism falls short of international standards.

He described the prison conditions for those convicted of terrorist activities as "farsighted, imaginative, extremely well-sourced" and more humane than any other place he's seen in the world handling terrorism suspects. Many of them are young men who did not engage in deadly acts inside the kingdom, but had planned to join extremist groups or fought abroad and returned disillusioned.

"On the other side of the coin, there's the darker side of Saudi Arabia and in particular the potentially pervasive culture of fear and the fact that individuals are being imprisoned for the exercise of the right to freedom of speech and opinion," he said.

His request to meet these individuals was denied. The government cited technical reasons for denying him his request, he said. Among those Emmerson requested to see was Raif Badawi, the liberal Saudi blogger whose public flogging drew international condemnation. Badawi is serving 10 years in prison for insulting the kingdom's powerful ultraconservatives on his blog.

Meanwhile, Saudi Arabia's de-radicalization program is among the most revolutionary for its handling of would-be and former terrorists. Its program focuses on changing the mindsets of people lured to extremism.

A key element of the kingdom's rehabilitation program is the Mohammed bin Nayef Center . There, men who have already served their prison sentences are permitted in some cases to attend important family events, given psychological care and have access to a pool, gym and even art therapy.

While there is no indication Saudi Arabia is on the verge of changing its definition of terrorism to exclude political speech, he welcomed the UN visit as a step in the right direction.