AMMAN: Amnesty International urged Saudi Arabia on Wednesday to disclose the whereabouts of a Jordanian activist it said was arrested last month and ensure to that he is protected from torture.

Web developer Khalid al-Natur, 27, was arrested on January 6 when he and four associates arrived at Riyadh's airport on a business trip, Amnesty said, adding that the others "were told they would risk a similar fate if they did not leave the airport immediately."

Amnesty said Natur, a member of movement calling for political and economic reform in Jordan, was arrested last year near the Saudi consulate in Amman for insulting a security officer during a protest "against Saudi Arabia's involvement in Bahrain."

Bahraini security forces, backed by Saudi and other Gulf troops, brutally quelled a month-long pro-democracy protest in March 2011.

"Neither the Jordanian authorities nor Natur's family, who have sought information about his case, have been provided with an official response regarding his detention, including his whereabouts and the reason for his detention," Amnesty said.

Jordanian officials were unavailable for comment.

The rights watchdog demanded that the ultra-conservative kingdom ensure that Natur "is protected from torture or other ill-treatment and given, without delay, regular access to his family, lawyers of his own choosing, consular assistance and any adequate medical treatment he may require."

It said Natur should be released "unless he is promptly charged with an internationally recognisable criminal offence and tried in proceedings that conform fully to international fair trial standards."

Amnesty said critics of oil-rich Saudi Arabia, an absolute monarchy, "face gross human rights violations." It charges that Riyadh has "systematically violated international human rights standards that irrevocably prohibit prolonged incommunicado detention of detainees."