Police in Perth say the deputy clerk of the Legislative Council, Nigel Lake, was wearing latex gloves and carrying a baseball bat and a balaclava when he was arrested last month.

A police car patrolling the suburb of City Beach on the night of February 17 saw a man acting suspiciously on foot and stopped him.

It was alleged he was wearing a black hoodie, latex gloves, black pants and black shoes and was carrying a baseball bat and balaclava.

Lake, 49, was charged with possessing a controlled weapon and possessing a disguise intended for use in connection with committing an offence.

Police said further investigations led them to charge him with installing and using a tracking device.

Police would not reveal the identity of a potential target.

Lake was stopped near the home of his boss Nigel Pratt – the Clerk of the Legislative Council.

Mr Pratt was the deputy clerk of Tasmania's Upper House from 2007 to 2013.

Lake has been stood down from his $166,000-a-year job pending his court appearance on March 18.

Legislative Council president Barry House said he took immediate action to suspend Lake when police notified him of the charges.

"We also took immediate steps to notify the CCC [Crime and Corruption Commission] because he's a public official, and we've fully cooperated with police in the investigation."

Lake acting clerk until Nigel Pratt appointed

Mr House said Mr Pratt had been appointed to the position in February 2014 after interviews with a "number of candidates" in November and December the previous year.

Lake had been acting in the role of Clerk of the Legislative Council until Mr Pratt's appointment.

Mr House said there was nothing unusual about the hiring process.

"That was a perfectly normal process," he said.

"We received several applications and we conducted interviews. A decision was made and the clerk was duly appointed."

Mr House would not confirm that Lake was one of the applicants considered for the position.

He said no appeal had lodged against the appointment by any other applicant.

Like a Monty Python episode: Premier

Arriving at Parliament, Premier Colin Barnett expressed bewilderment at the turn of events.

"I just find it bizarre, simple as that," he said.

"It's a bit like a Monty Python episode, isn't it?"

He said he was told of the arrest a couple of weeks ago.

Liberal Legislative Council member Robyn McSweeney said she was "absolutely appalled" while Police Minister Liza Harvey said she was surprised.

"However, you're probably aware in my portfolio I get lots of surprises and lots of reports of strange goings on every day of the week," she said.

Greens MP Lynn MacLaren said she was stunned to learn Lake was facing charges.

"It's just shocking to hear this news," she said.

"I think anyone would be shocked to find out that someone they work with every day has found themselves caught up in the law in this way."

Greens Legislative Ms McLaren said there was no hint of any problem in her dealings with Lake.

"I thought he was very helpful in the council. He gives us advice on petitions, so he's been very helpful and efficient in the advice that he's provided," she said.

Liberal Upper House MP Alyssa Hayden shared the disbelief of her Parliamentary colleagues.

"I'm blown away. Totally blown away," she said.