The State Security Ministry was expected to file papers in the Constitutional Court in Johannesburg on Monday to prevent an ex-intelligence official from testifying in the Jackie Selebi corruption trial.

Lawyers for the ministry made this undertaking in the High Court in Johannesburg last week, after the Supreme Court of Appeal dismissed a similar application on January 29.

The ministry wants Constitutional Court judges to overturn Johannesburg High Court Judge Meyer Joffe's decision to compel Barry Gilder to testify in the former National Police Commissioner's trial.

The State wants Gilder to testify about a 2005 draft intelligence report which contained a single paragraph about allegedly untoward payments Selebi was receiving from slain mining magnate Brett Kebble.

Correspondent attorney Shamima Gaibie of Cheadle, Thomson and Haysom said on Monday morning that the law firm had not yet filed the papers.

"I don't know at this stage [when the papers would be filed] but it should be later this afternoon or tomorrow morning," she said.

The ministry is arguing that forcing Gilder to testify could set a precedent - with serious constitutional ramifications - where intelligence information could be compromised.

The State was expected to file responding affidavits on Friday.

Prosecutor Gerrie Nel argued in court last year that testimony wanted from Gilder would cover information already in the public domain as several witnesses had already mentioned it in their testimony.

Selebi is facing a count of corruption and another of defeating the ends of justice in connection with some R1,2-million he allegedly received from Kebble, convicted drug trafficker Glenn Agliotti and ex-Hyundai boss Billy Rautenbach in return for favours.

He has pleaded not guilty to all charges.

His case is expected to resume on March 1.