A second suspicious envelope has been addressed to the office of Greens senator Sarah Hanson-Young, less than 24 hours after a death threat and an unknown powder were sent to the address.

Key points: The incident was treated as one involving a potentially hazardous material

The incident was treated as one involving a potentially hazardous material It is the second envelope to be addressed to the office in the past two days

It is the second envelope to be addressed to the office in the past two days It follows Senator Hanson-Young's election victory

Emergency services were called to the office on Wright Street, in Adelaide's CBD, around 11:00am this morning, sparking an evacuation of the building.

A spokesperson from the Metropolitan Fire Service (MFS) said it was treating the incident as one which involved a potentially hazardous material.

No-one was injured, but it followed police and fire crews attending the same office yesterday after a staffer opened an envelope containing white powder.

"Two letters have been received — one yesterday that included a substance that is unidentified. It's still at forensics at the moment," Senator Hanson-Young said.

"We've been told it is not explosive or radioactive, but they're running further tests to determine exactly what it is. That was accompanied by a death threat towards me."

Senator Hanson-Young would not go into detail about the exact wording but said it was "a very serious threat".

She said the second letter was now in the hands of police.

"It looks as though it is from the same sender," she said.

"I can't tell you the contents of today's letter because it's been taken away by the crime investigators.

"We live in a fair and safe democracy and we should cherish that — death threats and letters with substances included, that's not Australia. It's incredibly un-Australian."

MFS incident controller Rainer Kiessling said the envelope found today had shown a zero reading for dangerous chemicals.

"The envelope was unopened, linked to a similar incident yesterday … our policy is not to open an unopened envelope," he said.

Fire crews at the scene as the building was evacuated. ( ABC News: Rhett Burnie )

"It was delivered through the Australian postal system as per normal procedures … we are unsure who it was addressed to."

He said the envelope would be opened by South Australian police and the incident was clearly politically motivated.

"It's obviously somebody with a political gripe that has targeted this particular premises," he said.

"I believe suspicion was drawn to similarities between this envelope we've attended today and the one we attended last night."

Police investigating unknown substance

Police were called to the office on Wright Street just after 4:00pm on Monday, after an envelope addressed to Senator Hanson-Young was opened.

Police said the letter containing powder was addressed to Sarah Hanson-Young yesterday. ( AAP: Dean Lewins )

Last year, a New South Wales police officer threatened to rape Senator Hanson-Young's daughter during a phone call to her office.

Senior Constable Sean Daniel Murphy pleaded guilty to the offence in November, but avoided jail time.

"The most harrowing … was a threat against my daughter last year. That was the most horrific I've experienced," Senator Hanson-Young said.

The latest threat coincides with debate around the treatment of female politicians, after the Sunshine Coast Daily newspaper published a picture of Queensland Premier Annastacia Palaszczuk in crosshairs.

The substance inside yesterday's envelope is yet to be identified, but the Metropolitan Fire Service treated it as a HAZMAT (hazardous materials) incident.

Ms Hanson-Young secured a swing of nearly six per cent in Saturday's federal election.

Police have asked anyone with information about the incidents to contact Crime Stoppers on 1800 333 000.



