DUBAI, June 3, 2008 (AFP) - More than a dozen rights groups sent a petition to Saudi King Abdullah on Tuesday urging him to release several prominent Saudi reformists, some of whom have been held for 16 months.

"We put before you the case of the detention of an elite group of Saudis who have championed a peaceful internal dialogue to achieve reform," the signatories wrote in the petition, a copy of which was received by AFP.

The letter was faxed on Tuesday to the Saudi embassy in Paris, Haytham Manna, spokesman for the Arab Commission for Human Rights, told AFP by telephone from the French capital.

Manna said he was seeking an appointment with the embassy to also hand the document to diplomats, and an updated version signed by individual activists would be made public in Paris on June 13.

The petition reminded King Abdullah that he had pardoned three prominent reformists who spent 17 months in jail for demanding a constitutional monarchy shortly after ascending the throne of oil-rich Saudi Arabia in August 2005.

Two of the three -- Matruk al-Faleh and Abdullah al-Hamed -- are now again behind bars.

Faleh was arrested on May 19 and was subsequently reported by his wife to be on hunger strike.

he charges against him are unknown, but rights activists have linked his arrest to his defence of Hamed and a statement he wrote after visiting him at a prison in Buraida, some 320 kilometres (200 miles) north of Riyadh, which was critical of conditions in the jail.

 Hamed and his brother Issa are serving jail terms of six and four months respectively on charges of inciting women to stage public protests, which are banned in Saudi Arabia.

Faleh is Hamed's legal representative.

The petition to King Abdullah also raises the case of nine activists who were arrested in February 2007 for alleged links to terror funding, eight of whom remain incarcerated without trial.

"We urge you to strive for the release of (the latter group), Abdullah and Issa al-Hamed and Matruk al-Faleh, and to end these injustices," the petition said.

Saudi activists have said that the group held since February last year had been mulling the formation of an Islamic constitutional political party.

Political parties are banned in Saudi Arabia, which is ruled by an absolute monarchy and has no elected parliament.

Signatories include 14 human rights groups, mostly Arab. Manna said the petition would be updated later this month after some 300 reformists and activists from Saudi Arabia and elsewhere asked that their names be added.