Amnesty International has condemned an Oman court's decision to shut down the daily al-Zaman newspaper and jail three of its journalists, including its editor-in-chief, for reporting on alleged corruption within the judiciary.

The rights group's Oman researcher, Drewery Dyke, said in a statement after the verdict Monday that the journalists are being punished for carrying out legitimate work, calling it "a dangerous escalation of the authorities' attempts to stifle independent journalism."

The state-run news agency of the Gulf Arab country, which is a close U.S. ally, had previously issued a statement saying the newspaper published material in a way "that harms a pillar of the state."

The Committee to Protect Journalists and Reporters Without Borders have called for the "unconditional release" of al-Zaman's journalists.