UPDATE:  Former Justice Minister Michael Keenan's office also tipped off the media.

ORIGINAL: Senator Michaelia Cash’s former chief of staff leaked details about a union raid to the media.

This week, Senator Cash’s former media adviser David de Garis was ordered by Federal Court Justice Mordecai Bromberg to name his source on the AFP raid of Australian Workers Union (AWU) offices in 2017.

Mr de Garis named Ben Davies, another former staff member of Senator Cash, as the source. He also admitted that he leaked that information to journalists, and resigned soon after.

Mr Davies will give evidence later this week.

The AWU argues that the raids were unlawful – carried out by the Registered Organisations Commission and Australian Federal Police on political grounds instigated by Senator Cash.

Mr Davies has begun his own legal action over the affair, suing AWU national secretary and BuzzFeed journalist Alice Workman for defamation. He has filed an application and statement of claims in the Federal Court's NSW registry, and the should have its first hearing in March.

Senator Cash is due to give evidence on Friday.