"Police and other emergency services are on the scene and are dealing with the situation".
The Scottish fire and rescue service was attending the scene.
The MSP building in Holyrood, Edinburgh, has been cleared following the incident.
Reports said the packages were addressed to Jamie Halco Johnston, Liz Smith and Edward Mountain.
Mr Mountain said the invitation was to a Highland council event to mark the Inverness Courier's anniversary.
The vehicle entry system had been closed to enable emergency services access, the chief executive said.
One, containing suspicious white powder, was opened in the office of Jamie Halco Johnston, an MSP for the Highlands and Islands region.
Police have evacuated part of the Scottish parliament after an incident said to involve the discovery of a white powder in several packages sent to Conservative MSPs. They then evacuated the building and were examining the contents of the packages.
"It's a white powder incident, there were a couple of suspicious packages sent to a Tory (Conservative) MSP", a source at the parliament told Reuters, using the acronym for Member of the Scottish parliament.
According to the Mirror, a suspicious substance was found in a letter sent to an MSP's office, RT reported.
"The building has been evacuated as a precaution and inquiries are continuing".
Firefighters and police officers are now on the scene in Edinburgh, while MSPs have gathered in a lobby area of the parliament.
"The public are thanked for their patience and support during this matter".