Bill mounts for Serana inquiry: dept

Taxpayers have paid $240,000 for the federal Agriculture Department to investigate conduct blamed for the closure of a West Australian biotech company.

Bunbury-based Serana, which exported cattle serum, has been embroiled in a battle with the department over a botched biosecurity investigation.

The department raided Serana's offices in 2013 on questionable suspicions that the biotech firm was illegally importing bovine serum from countries with foot-and-mouth disease.

The Federal Court found in an interim judgment last year that, on the face of it, the warrant for the raid sought by a departmental officer was unlawfully issued.

A Senate estimates hearing was told on Monday a continuing internal investigation into the matter has already cost $239,285, with no indication of when it will be completed.

But a department official said there was nothing stopping the company from trading because of the action taken against it.