News emerged Thursday morning that NSW Agriculture Minister Adam Marshall had tested positive to the virus, while three other Nationals MPs were forced to isolate after attending an exposure site.

Mr Toole has been working in parliament since Monday and was due to return home on Thursday afternoon, but had to delay his trip until he received health advice regarding travelling.

He said he had not been in close contact with Mr Marshall.

"After concerns about a positive case at parliament, I've been self-isolating in my office at Parliament House and closely following all NSW Health advice including being tested," Mr Toole said late Thursday afternoon.

"I am awaiting my results and will continue to follow all Health advice. It's critical we all do our bit to contain the virus and keep the community safe."

He said he would not leave his office until he received advice.

"These latest cases are a reminder to all of us that COVID is far from over," he said.

"No matter where you live or work, it's important to remain vigilant, continue checking in with QR codes and practise social distancing and good hygiene to protect yourself and others in the community.

"There's nothing more important than keeping our community safe."

During a press conference early Thursday afternoon, NSW Premier Gladys Berejiklian said contact tracing and testing were under way regarding Mr Marshall's case.

She said her colleagues would not be able to enter the chamber to pass the budget until all the assessments had been made.

According to Mr Toole, masks have been worn in parliament all week and staff numbers were reduced in light of the outbreak.

"Even in question time, instead of having 93 on the floor, we only had about 20 people," he said.

He also took it upon himself to keep his distance.

He said that there were other regional MPs who were in the same situation as him, unsure when they would return home.

It is possible they may have to undergo a two-week isolation period, but as of Thursday afternoon they had not received any advice.

"I don't have any symptoms, but I'm not going to do anything without advice from NSW Health," Mr Toole said.

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