The suspicious white powder sent in a letter to Vasse MLA Troy Buswell's electorate office has been found to be flour.
The letter was the sixth suspicious package found in recent days, after packages containing what was ultimately proven to be flour were sent to the Premier, treasurer Mike Nahan, Parliament House, the West Australian and the Taxi Board.
WA Police spokesperson Susan Usher confirmed this morning the package was harmless but said the issue was being taken seriously and inquiries were continuing.
The letter was found by members of Mr Buswell's electorate office late on Tuesday afternoon, with the staff calling local police who evacuated the building as a precaution.
Chem Centre staff travelled to Busselton to test the powder with police spokesman Dominic Wood saying at the time that it was likely the letter was linked to those found last week.
"We also ask that if anyone discovers any similar item, which raises concern or suspicion, that they contact the Police Operations Centre on 131444 immediately," Usher said.
