Protester numbers outside New Zealand's parliament have swelled as police scaled back efforts to clear anti-vaccine demonstrators involved in violent clashes a day earlier.

A festive mood prevailed at a makeshift tent settlement inhabitants have dubbed “Camp Freedom”, with music and dancing as police looked on from behind barricades, AFP reported.

Wellington police described the hands-off tactics as a “measured approach”, pointing to the presence of children among the crowd.

“Police are continuing to monitor and contain protest activity at parliament grounds,” Superintendent Corrie Parnell said in a statement.