A federal judge has rejected the US government's plea to prevent the public from attending the first legal challenge to its practice of forcibly feeding detainees on hunger strike at Guantánamo Bay, describing it as "extraordinary" and "deeply troubling".

Judge Gladys Kessler, of the Washington DC district court, noted that the Justice Department's request came late – just days before opening statements are to be delivered in the case of Abu Wa'el Dhiab.

"With such a longstanding and ongoing public interest at stake, it would be particularly egregious to bar the public from observing the credibility of live witnesses, the substance of their testimony, whether proper procedures are being followed, and whether the court is treating all participants fairly," Kessler wrote in a ruling on Thursday.

In an occasionally mocking tone, Kessler dismissed the government's argument that an open hearing would jeopardise national security by risking the disclosure of classified information.