Saudi writer jailed for seven years amid 'intensified crackdown'
The Gulf Centre for Human Rights (GCHR) said Nadhir al-Majid, 40, received the sentence last week from the Specialised Criminal Court in Riyadh.
Rights monitors have criticised the practice of trying activists in such courts, which handle "terrorism" cases.
"Reports have confirmed that the writer was alone during the hearing and not accompanied by his family or his lawyer," said the Gulf Centre, which has offices in Copenhagen and Beirut.
It said the prosecution filed many charges against Majid, including participating in demonstrations and "having contact with correspondents" of foreign media organisations.
Another watchdog, Human Rights Watch, in 2011 identified Majid as one of more than 160 dissidents arrested, mostly in Eastern Province where the Shia minority had protested for political reforms and the release of prisoners.
He was freed in 2012, the Gulf Centre said.
In early January London-based Amnesty International said "a string of activists" had been detained or appeared in court over previous weeks in connection with peaceful human rights work.
"Saudi Arabia's authorities have begun the year with an intensified crackdown against human rights activists", it said.
On a visit to the kingdom last week, a United Nations independent expert called on Saudi Arabia to "liberalise" its approach to social media, where activists communicate.
Philip Alston, the UN special rapporteur on extreme poverty and human rights, said he received reports of "instances in which it has cracked down on certain people" communicating over the internet.