US Senator Ron Wyden said on Friday he will move to compel the United States intelligence chief to release information about the murder of Washington Post columnist Jamal Khashoggi if the administration does not produce a report on the killing before the end of the impeachment trial of President Donald Trump.

Wyden was invoking the Senate's power to unilaterally declassify intelligence material to push the Trump administration to release a report into the October 2018 killing of Khashoggi at the Saudi consulate in Istanbul, Turkey. Such a report was due by law to have been released earlier this month, a deadline the Democratic senator said the administration had flouted.

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The goal, Wyden told reporters, was "naming names with respect to who ordered it, who was complicit, and what might have been done to prevent it".

Wyden is unlikely to get his way - at least not directly.

Even though the Senate has the power under a 1970s-era authority to unilaterally declassify information, no such move has ever made it out of the Intelligence Committee on which the Oregon Democrat serves as a member.

Steven Aftergood, senior research analyst with the Federation of American Scientists' Project on Government Secrecy, said threatening to use the authority might push the administration to find "an acceptable middle ground - an unclassified version of the assessment, a classified briefing, or something else."

Wyden said an unclassified assessment was what he was after, predicting that the push would draw support from at least some Republicans on the committee.

"I don't think there's a lot of Republican support for carrying water for nondisclosure here," he said.

The CIA has concluded that Saudi Crown Prince Mohammed bin Salman (MBS) ordered the killing of Khashoggi, sources told Reuters weeks after his death.

Even an unclassified version of that assessment could be explosive, given close ties between the United States and Saudi Arabia and between the Trump administration and Crown Prince Mohammed, in particular.

A spokesman for the Senate Intelligence Committee declined comment. The Office of the Director of National Intelligence said in an email that its response to Congress was "in process".

The Saudi embassy in Washington, which rejects allegations that Crown Prince Mohammed was involved in Khashoggi's killing, did not immediately return messages seeking comment.