* Saudi Arabia detains founders of party, activists say
* Political parties not allowed in Saudi Arabia
JEDDAH, Feb 19 (Reuters) - Saudi authorities have detained several activists who tried to set up the kingdom's first political party, human rights activists said on Saturday.
The top oil exporter and U.S. ally is an absolute monarchy that does not tolerate any form of public dissent, does not have an elected parliament or any political parties.
Saudi Islamists and opposition activists this month launched a political party called the "Islamic Umma" in a rare challenge to authority inspired by unrest triggering regime change in Tunisia and Egypt.
"There are four in custody now. Five were arrested, two were outside the country and the others were questioned and released," said Mohammed al-Qahtani, a Riyadh-based activist and head of the Saudi Civil and Political Rights Association, who has been following the case.
Officials at the General Directorate of Investigations, an investigative arm of the government, could not be immediately reached for comment.
New York-based Human Rights Watch demanded the release of the activists, some of whom have been campaigning for several years for greater political freedom in Saudi Arabia.
"Saudi suppression of political activity is as swift as it is total," Christoph Wilcke, senior Middle East researcher at Human Rights Watch, said in a statement.
"At a time when people throughout the Arab world are out on the street seeking greater freedom, the Saudi secret police seem determined to nip any similar demands in the bud."
The new party had called on its website for holding elections, more transparency of government decisions and an independent judiciary.
There have been previous attempts to form parties but the group was the first to announce it publicly, analysts said. Its members include Islamist intellectuals, lecturers, human rights activists and lawyers.
In 2007, Saudi Arabia arrested a group calling for a constitutional monarchy and most are still in detention, according to activists.
King Abdullah, who has been away for medical treatment since November, is due to return to Saudi Arabia next week. Activists hope he will announce some reforms to address dissent at home. (Reporting by Asma Alsharif; Editing by Alison Williams)