WA Police are investigating several traffic accidents which occurred on the night officers were called to former treasurer Troy Buswell's home.

Residents of Olive Street in Subiaco said a car hit a telegraph pole and sideswiped a parked vehicle in the early hours of February 23.

It is believed the damage was sustained before officers were called to Mr Buswell's Roberts Road home a few blocks away, following reports of a car driving erratically.

Police began investigating the crash in Olive Street on February 23.

But on Monday, two weeks after the accident and following the resignation of Mr Buswell, police re-interviewed the woman who owns the car which was damaged.

It is one of several collisions under investigation.

In Parliament, Police Minister Liza Harvey refused to say if Mr Buswell's car was involved in any accidents in the drive from a function at Kings Park to Roberts Road.

"What I can confirm is that WA Police are involved in an ongoing investigation of matters of the 23rd of February, and I'm not prepared to comment on an ongoing investigation by police," she said.

"Police will reveal the outcome of their investigation in due course."

Labor's police spokeswoman Michelle Roberts said the Police Minister should have at least confirmed in Parliament that there were other investigations.

"A police minister who wouldn't confirm just the basics that these other instances were being looked at... now that was plain for people to see," she said.

"I mean, news crews went out into the streets there, spoke to people and police were clearly visible interviewing people about complaints they hadn't followed up on two weeks ago.

"I don't know why the Police Minister's being so secretive about this."

Mr Buswell's ministerial car, which has obvious damage to its front bumper, has been towed from his home by police.

Police would not comment on whether they believed the accidents were linked.

They said the investigation into how Mr Buswell's ministerial car was damaged was ongoing.

Troy Buswell undergoing treatment for a 'breakdown'

Mr Buswell stepped down on Sunday after details of the crash were revealed and he has been undergoing treatment in hospital for what has been described as a breakdown.

The car was involved in a crash outside his home in Subiaco in the early hours of February 23.

Two officers from the police traffic enforcement unit attended after receiving a call just after 1:30am.

When the two constables arrived at the address, they noted the vehicle was locked behind a gate and was damaged.

Police commissioner Karl O'Callaghan said they had no information at that time linking the vehicle or premises to Mr Buswell.

The car was registered to the Office of State Administration.

Sorry, this video has expired Premier Barnett announces Troy Buswell's resignation

Premier Colin Barnett said he was not informed about the crash until a fortnight later, on Sunday afternoon.

Mr Barnett said Mr Buswell could not shed further light on the incident.

"He said he basically didn't have much recollection," he said.

Mr Buswell has since been treated in hospital in Perth and at a clinic in Sydney.

He has now been released but is still receiving medical treatment.

Mr Buswell will remain in Parliament as the Member for Vasse.

Premier assumes Treasury responsibilities

Mr Barnett has assumed temporary responsibility of the treasury and transport portfolios, and says there will be a new appointment to Cabinet.

He plans to announce any ministerial changes by the end of the week.

Finance Minister Mike Nahan is a likely contender for the role of treasurer and says he is ready to step up to the plate.

However, political analysts say there is now no obvious successor for the role of premier.

Murdoch University's senior politics lecturer Dr Ian Cook told the ABC that Mr Buswell had been expected to take over as premier when Mr Barnett eventually steps down.

Former WA treasurer Christian Porter was previously seen as the most likely successor, Dr Cook said, but his departure for federal politics had left Mr Buswell as the only candidate.

"Despite some indiscretions, he was still the central player, and he was still the one we were expecting to take over, so there's a huge hole," Dr Cook said.