The US government is in possession of 250,000 pages of documents relating to the transmission of state secrets to whistleblower website WikiLeaks, which it is refusing to disclose to defence lawyers representing the alleged source of the leaks, Bradley Manning.

Manning's civilian lawyer, David Coombs, has lodged a motion with the military court that is hearing the court-martial of the US soldier. Coombs writes in the motion that the government has revealed to him in a throwaway footnote that there are 250,000 pages in its possession that relate to Manning, WikiLeaks and secret official assessments of the damage that the massive leak caused to US interests around the world.

Yet none of these pages have been made available to the defence. "If so, this is very disconcerting to the defence," Coombs says.

Manning, an intelligence analyst who was working outside Baghdad when he was arrested two years ago, is charged with 22 counts connected to the largest leak of state secrets in US history.

In the motion, published in redacted form on his website, Coombs renews his long-standing efforts to compel the US government to hand over information that could prove crucial in preparing Manning's defence.

He accuses the army of continuing to resist its legal obligations to disclose anything that could help Manning prove his innocence or achieve a lighter sentence.

The motion is one of several defence motions that have been submitted to the court and that will be the subject of a pre-trial hearing at Fort Meade in Maryland. Manning himself is likely to attend the hearing, which comes three months before a full trial, which is scheduled for 21 September.

The language of Coombs's legal submission suggests that the lawyer, who himself has a military background, is growing increasingly frustrated by the obfuscations and alleged sleights of hand played by the prosecution.

In recent motions, the lawyer has accused the US government of preventing Manning from having a fair trial.

Coombs paints an almost Kafkaesque world in which the military authorities play word games in order to keep deflecting his requests for disclosure.

Sometimes the government says that the defense is being "too narrow" in its requests, at other times "too broad".

Coombs comments sarcastically: "The defence believes that no defence discovery request would ever be 'just right' to satisfy Goldilocks."

When the defence asked to see "damage assessments" or "investigations" that the government had carried out into the likely impact of WikiLeaks, he was told none existed.

After much effort was expended, Coombs managed to get the government to admit that what he should have asked for – according to its vocabulary – was "working papers".

"By morphing, distorting and constantly changing definitions, the government is trying to 'define' itself out of producing relevant discovery," Coombs complains. "It cannot be permitted to do this."

Judging from the motions which Coombs has filed, this week's pre-trial hearing promises to be quite feisty.

Other motions before the court include a demand for the dismissal of 10 of the 22 counts against the private.

Though Manning faces very severe charges, including "aiding the enemy", that carry a possible sentence of life in military custody, he draws comfort from having such a robust defence team.

His aunt, speaking to the Guardian last week, said that Manning had "tremendous confidence in David Coombs".