A recently released Egyptian blogger who served the longest prison term in the Arab world for his writings said Wednesday that jail was a "cruel experience" but his views remain unchanged.

Abdel Kareem Nabil, known by his blogging name Kareem Amer, was arrested in March 2006 and convicted of insulting Islam and the president in his blog. He served four years in prison and was released on Nov. 16.

Described by rights groups as a prisoner of conscience, Nabil was an outspoken secularist and sharp critic of conservative Muslims. He often lashed out at Al-Azhar — the most prominent religious center in Sunni Islam — calling it "the university of terrorism" and accusing it of encouraging extremism.

He called Al-Azhar the "other side of the coin of al-Qaida" and said the 1,000-year-old university should be dissolved or turned into a secular institution.

He also criticized Mubarak, calling him "the symbol of tyranny."

The United States described the conviction of Nabil as "a setback for human rights."

During his imprisonment, he told reporters, he was beaten up, slapped in the face, deprived of visits and insulted by police officers.

"One police officer was beating me up then tried to force me to smile while filming me with his mobile," he said. Another time, he lost a front tooth when he was attacked by a fellow prisoner, who was also working as a police informant.

Nabil spent an extra 10 days in detention past his official release date. Before he was finally let go, he was blindfolded and summoned by a pair of police officers who vowed to return him to prison if he didn't change his views.

"They slapped me in the face, showered me with insults and threatened to torture me," he recalled.

Now 26, Nabil plans to continue his studies, stay away from Al-Azhar, and continue his writings.

"If I go back in time, I will not change a bit. I have no regret," he said. "It was a cruel and tough experience," he added.

In his blog, he wrote a commentary following clashes between Muslims and Christians in 2005 saying that "Muslims revealed their true ugly face and appeared to all the world that they are full of brutality, barbarism and inhumanity."

He called Muhammad's 7th century companions — who are deeply revered by devout Muslims — "spillers of blood" for their teachings on warfare.