'I have never seen Parliament locked up like this' - Judith Collins as protesters descend on Parliament

National Leader Judith Collins said she is "concerned" by today's march on Parliament by anti-vaccination protests and urged people to demonstrate peacefully.

"I'm obviously concerned, I have never seen Parliament locked up like this," said Collins.

Collins has been an MP since 2002, and therefore experienced a fair number of large protests.

Collins said she'd glimpsed some anti-vaccination sentiment online.

"Only on social media, but I'm pretty adept at ignoring that," Collins said.

She urged people to be peaceful.

"My message to people protesting outside Parliament is to be peaceful," Collins said.

Collins said she was not concerned for her own safety, and believed herself to be safe.

She urged her MPs to stay on the Parliamentary precinct.

"You are best to stay on the parliamentary precinct.

"It is important for them to understand this is a very unusual situation and that parliamentary security staff are there to protect them and do what they need to do," Collins said.

Collins said she had made it "very clear" to her MPs that she does not think it is the right thing for them to go out and join the protest.