Perth airport road closed after threat

The road that links Perth's domestic and international airports, and parts of a shopping centre in the city's southern suburbs have been closed after suspicious mail items were found.

Sections of the Riverton Forum Shopping Centre were evacuated after suspicious piece mail was found at the electorate offices of WA Premier Colin Barnett and Treasurer Mike Nahan.

That followed the discovery of three suspicious items at the Australia Post depot on Boud Avenue, Redcliffe, which links the two airports.

The suspicious items at the mailing centre near Perth Airport were analysed, and confirmed not to contain dangerous substances, police said in a statement.

A spokesman for Mr Nahan said he was not in his office at the time.

Employees at the mail sorting depot and other nearby businesses were evacuated as the police tactical response group's bomb unit investigated.

The items at the depot were deemed to be suspicious because of threatening words written on them, police said.

One was addressed to The West Australian newspaper.

At least three of the mail items contain a powder-like substance.

Police spokesman Sam Dinnison said officers were investigating whether they had the same origin "given the timing".

Road blocks have been set up on Boud Avenue and Dunreath Drive in Redcliffe, although both airports can still be reached via other roads.

Mr Dinnison said police would look into whether any other suspicious items may have already been delivered.