ABC gardening personality Peter Cundall has been arrested outside Tasmania's Parliament during a protest against Gunns' Tamar Valley pulp mill.

Mr Cundall was among 50 activists who were arrested at the rally organised by the group Pulp the Mill.

The 82-year-old told the crowd he had never been arrested but was willing to make a stand.

He was arrested after refusing police requests to move from Parliament's front steps.

"Did you hear the direction before?" an officer asked him.

"I did hear it," he replied.

"Are you refusing to leave now?"

"I'm afraid so, I do respect the law but I'm so sorry but I will be refusing to leave," Mr Cundall said.

"Then you realise that if you refuse to leave you can be arrested," the officer said.

"I understand that," he replied.

"OK, I'm now arresting you," the officer told him.

Several other protesters have also been taken away by police.