The Federal Court has issued a subpoena requiring Jobs Minister Michaelia Cash to give evidence in the Australian Workers Union (AWU) raids case.

Key points: Senator Cash asked the Registered Organisations Commission to consider investigating donations from the AWU to GetUp

Senator Cash asked the Registered Organisations Commission to consider investigating donations from the AWU to GetUp Her staffer later admitted tipping off media to AFP raids on the AWU offices

Her staffer later admitted tipping off media to AFP raids on the AWU offices The AWU has gone to Federal Court to try to prevent the documents seized in that raid from being examined by the ROC

Court documents show the court is ordering Senator Cash to appear in Melbourne in August, after the union asked for orders to be made requiring the Minister to give evidence.

But Senator Cash has instructed her lawyers to fight that subpoena, so that she is not forced to give evidence.

The AWU wants the court to throw out an investigation by the Registered Organisations Commission (ROC) into donations by the union to activist group GetUp.

Senator Cash has faced fierce criticism after her staffer, David De Garis, tipped off the media that raids by the Australian Federal Police (AFP) on the AWU's Sydney and Melbourne offices were imminent.

The Minister has maintained she was unaware of Mr De Garis's actions, and Mr De Garis quit soon after.

The trial is listed in Melbourne from August 1 to 3, and the subpoena said Senator Cash must attend.

"I have issued instructions for the subpoena to be set aside," Senator Cash said on Wednesday.

"I do not intend to play the court process out publicly."

The media adviser for the Fair Work Ombudsman, Mark Lee was also embroiled in the saga.

He was due to take up a position in Senator Cash's office, which never happened after the leak allegations were aired.

Mr De Garis, Mr Lee and ROC official Christopher Enright have also been called to give evidence.

AWU national secretary Daniel Walton said the union still believed the raids and investigation were unlawful.

"We think it's vital the court is assisted by the evidence of witnesses who we believe are relevant to the issues in the case. That is why we sought subpoenas," Mr Walton said in a statement.

"If we are to understand exactly what happened then we believe the testimony of these individuals is critical."

Labor demands Cash appear before Estimates immediately

Labor used Senate Estimates to attempt to grill Senator Cash about the subpoena, with Doug Cameron asking Assistant Minister Zed Seselja to contact the Jobs Minister's office immediately.

Senator Seselja: I'm not her diary secretary. Senator Cameron: I'm not asking you to be a diary secretary. Senator Seselja: You seem to be … any discussions you want to have with Minister Cash, that's up to you.

Sorry, this video has expired 'I'm not her diary': Assistant Minister dodges questions on Michaelia Cash's whereabouts

The Education and Employment Senate committee has resolved to request Senator Cash appear again at Estimates in the wake of the Federal Court subpoena.

Senator Cash's office said she was not due to appear before Estimates on Wednesday.

"Senator Cash is not the responsible minister for the workplace relations agencies appearing before Senate Estimates today," a spokesperson said.

"As the responsible minister, Craig Laundy, is based in the House of Representatives, he is being represented by Assistant Minister Seselja."

Labor's employment spokesman Brendan O'Connor seized upon the development.

"We have a minister who has refused to cooperate, to comply with ministerial responsibility, and now she will not even appear and attend Parliament," he said.

"Now that means her position is untenable, and the Prime Minister needs to consider her position.

"It's a cover-up."