Counsel for the former spy Witness K has launched a broadside at Legal Aid ACT, accusing it of an “extraordinary unexplained roadblock” in approving funding for the whistleblower’s case.

Witness K has decided to plead guilty in the ACT magistrates court to one charge of communicating secret information obtained in the course of his duties as an Australian Secret Intelligence Service agent by revealing Australia’s spying on Timor-Leste in 2004 during talks to carve up resources in the Timor Sea.

At a directions hearing on Thursday, Witness K’s counsel, Haydn Carmichael, told the court his client had applied for legal aid more than a year ago and might still need funding for his plea and sentencing hearing, including “significant disbursements” to bring witnesses from overseas and medical evidence.

Carmichael explained that with the exception of “limited fees” to attend hearings in Canberra, Witness K’s case had been conducted pro bono by himself, Robert Richter and solicitors from Corrs Chambers Westgarth, with some assistance from the Australian government solicitor in applying for legal aid.

Carmichael signalled he intended to ask the court to force the ACT Legal Aid chief executive, John Boersig, to explain why the application for aid “has not been resolved at all satisfactorily”.

Witness K’s case was “complex”, “novel” – a first-of-its kind prosecution – and legal aid was required to facilitate the administration of justice, he said.

Carmichael quoted a letter promising that Witness K would have “every proper opportunity to obtain appropriate funding” and that a decision would be made independent of the commonwealth attorney general.

But Carmichael accused Boersig of failing to “respond to facts put to him” in the application, a matter of “grave concern”. He called for a “real and rational response” explaining ACT Legal Aid’s decision and what help would be available to Witness K.

Carmichael warned that refusing legal aid might compromise further hearings and would amount to entering a “parallel universe” of intruding on, rather than facilitating, the interests of justice.

Witness K’s case is scheduled to return for a mention on 13 September to see if facts of the case are agreed with the prosecution, before a formal plea and sentencing at a later date.

Witness K’s former lawyer, Bernard Collaery, has taken a different path, intending to protest his innocence in the ACT supreme court. In August Collaery said he understood the former spy’s desire to seek a swift resolution after “six years of seclusion, harassment and questioning”.

Boersig told Guardian Australia that legislation prevented him from commenting on any application for legal aid.